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Speed-distance-time, Ohm's law, unit prefix converter, wavelength, and density calculators.
Classic physics calculator: input any 2 of speed, distance, time to calculate the 3rd.
Calculate voltage, current, resistance, and power using Ohm's Law. Input any 2, get the rest.
Convert any number to all SI prefixes from yocto to yotta. Scientific notation display.
Convert between frequency and wavelength using the speed of light. Shows electromagnetic spectrum position.
Calculate density from mass and volume, or solve for any variable. Common materials reference table.
Calculate the current moon phase, illumination percentage, and upcoming lunar phases.
Calculate your weight on Mercury, Venus, Mars, Jupiter, Saturn, Uranus, Neptune, and the Moon.
Enter your birth date to find your zodiac sign, element, ruling planet, and personality traits.
Calculate distances to planets and stars in km, AU, light-years. See travel times at various speeds.
Calculate sunrise and sunset times for any location and date using solar position algorithms.
Convert light-minutes to kilometers.
Convert parsecs to light-years.
Convert astronomical units to kilometers.
Convert microns to millimeters.
Convert millimeters to microns.
Convert nanometers to meters.
Convert RPM to radians per second.
Convert radians per second to RPM.
Convert newtons to pounds-force.
Convert pounds-force to newtons.
Convert Newtons to kilogram-force.
Convert kilogram-force to Newtons.
Convert Joules to calories.
Convert calories to Joules.
Convert revolutions per minute to Hertz.
Convert Hertz to revolutions per minute.
Convert Pascals to atmospheres.
Convert atmospheres to Pascals.
Convert electron volts to joules.
Convert joules to electron volts.
Calculate velocity from distance and time or vice versa.
Calculate acceleration from velocity change and time interval.
Calculate force using Newton's second law (F = m * a).
Calculate linear momentum from mass and velocity.
Calculate kinetic energy from mass and velocity.
Calculate gravitational potential energy from mass, height, and gravity.
Calculate mechanical work from force, distance, and angle.
Calculate power from work done and time elapsed.
Calculate friction force from normal force and friction coefficient.
Calculate centripetal force from mass, velocity, and radius.
Calculate gravitational force between two masses using Newton's law.
Calculate terminal velocity from mass, drag coefficient, and area.
Calculate projectile range from launch speed and angle.
Calculate maximum height of a projectile from launch speed and angle.
Calculate the period of a simple pendulum from its length.
Calculate spring constant from force applied and displacement.
Calculate spring force from spring constant and displacement.
Calculate pressure from force and area using P = F/A.
Calculate buoyant force from fluid density and displaced volume.
Solve Bernoulli's equation for fluid pressure, velocity, or height.
Calculate the area of any regular polygon from side count and length.
Calculate the area of an irregular polygon from vertex coordinates.
Calculate the area of an annulus from inner and outer radii.
Calculate the volume of a torus from major and minor radii.
Calculate the volume of a frustum from top radius, base radius, and height.
Calculate the volume of a regular tetrahedron from edge length.
Calculate the surface area of a regular dodecahedron from edge length.
Calculate the surface area of a regular icosahedron from edge length.
Calculate the shortest distance between two points on a sphere.
Calculate chord length from radius and central angle.
Calculate the sagitta (arc height) from radius and chord length.
Calculate the central angle from arc length and radius.
Calculate an inscribed angle from its intercepted arc.
Calculate the tangent line to a circle from an external point.
Calculate secant segment lengths using the power of a point.
Calculate the diagonal length of a rectangle from width and height.
Calculate the face diagonal and space diagonal of a cube.
Calculate the space diagonal of a rectangular prism.
Calculate golden rectangle dimensions from one side length.
Generate Fibonacci spiral dimensions and coordinates.
Calculate what fraction of the speed of light a velocity represents.
Convert a fraction of the speed of light to meters per second.
Calculate what fraction of the speed of sound a velocity represents.
Convert a fraction of the speed of sound to meters per second.
Calculate terminal velocity from mass, drag coefficient, and area.
Calculate escape velocity for a given planet mass and radius.
Calculate orbital velocity for a given altitude and body mass.
Calculate first, second, and third cosmic velocities for a celestial body.
Calculate velocity in m/s from Star Trek warp factor.
Calculate sub-light impulse speed as a fraction of light speed.
Convert electromagnetic wavelength to frequency.
Convert frequency to electromagnetic wavelength.
Calculate angular frequency (omega) from frequency or period.
Convert frequency to photon energy using Planck relation.
Calculate photon energy from wavelength or frequency.
Calculate photon wavelength from energy in eV or joules.
Convert electron volts to kilowatt-hours for particle physics energy.
Convert kilowatt-hours to electron volts.
Convert ergs to joules for CGS to SI energy conversion.
Convert joules to ergs for SI to CGS energy conversion.
Calculate linear or volumetric thermal expansion of materials.
Calculate heat capacity from mass, specific heat, and temperature change.
Calculate specific heat capacity from energy, mass, and temperature data.
Convert newtons to dynes for SI to CGS force conversion.
Convert dynes to newtons for CGS to SI force conversion.
Convert newton-meters to dyne-centimeters for CGS torque.
Convert dyne-centimeters to newton-meters.
Convert barns to square meters for nuclear cross-section area.
Convert square meters to barns for particle physics.
Convert becquerels to curies for radioactivity measurement.
Convert curies to becquerels.
Convert grays to rads for absorbed radiation dose.
Convert rads to grays.
Convert sieverts to rems for radiation dose equivalent.
Convert rems to sieverts.
Convert roentgens to coulombs per kilogram for radiation exposure.
Reference table of amino acids with structures and properties.
Reference table of freezing points for common substances.
Reference table of boiling points for common substances.
Reference table of melting points for metals and common materials.
Reference table of flash points for flammable liquids and chemicals.
Reference table of auto-ignition temperatures for common materials.
Calculate range, max height, and flight time of a projectile.
Calculate velocity, distance, and time for free-falling objects.
Calculate forces on an object on an inclined plane with friction.
Calculate mechanical advantage and forces in pulley systems.
Calculate forces and distances for first, second, and third class levers.
Calculate mechanical advantage of a wheel and axle system.
Calculate force amplification and mechanical advantage of a wedge.
Calculate mechanical advantage and torque for screw mechanisms.
Calculate gear ratios and output speed for gear trains.
Calculate speed ratios and belt length for belt drive systems.
Calculate sprocket ratios and chain length for chain drives.
Calculate cam profiles and follower displacement for cam mechanisms.
Analyze position and velocity in crank-slider mechanisms.
Analyze motion and positions of a four-bar linkage mechanism.
Calculate gear ratios and speeds for planetary (epicyclic) gear sets.
Calculate gear ratio and efficiency of worm gear systems.
Convert rotary motion to linear motion with rack and pinion specs.
Calculate force multiplication in hydraulic press systems.
Calculate force output and air consumption of pneumatic cylinders.
Calculate natural frequency and period of a spring-mass system.
Analyze damped harmonic oscillation with damping coefficient.
Analyze forced harmonic oscillation with driving frequency.
Calculate the resonance frequency of mechanical and electrical systems.
Calculate the critical rotational speed of a shaft or rotor.
Calculate precession rate of a spinning gyroscope under torque.
Calculate the theoretical maximum efficiency of a Carnot heat engine.
Calculate thermal efficiency and work output of an Otto cycle engine.
Calculate thermal efficiency and work output of a Diesel cycle engine.
Calculate thermal efficiency of an ideal Rankine steam power cycle.
Calculate thermal efficiency of an ideal Brayton gas turbine cycle.
Calculate the coefficient of performance for refrigeration cycles.
Calculate heat transfer rate and LMTD for heat exchangers.
Calculate heat transfer by conduction through a material using Fourier law.
Calculate convective heat transfer using Newton law of cooling.
Calculate radiative heat transfer between surfaces.
Calculate radiant power from temperature using the Stefan-Boltzmann law.
Find peak wavelength of black body radiation from temperature.
Calculate spectral radiance of a black body at a given wavelength.
Estimate black body temperature from peak emission wavelength.
Calculate entropy change for reversible and irreversible processes.
Calculate Gibbs free energy change from enthalpy and entropy.
Calculate Helmholtz free energy from internal energy and entropy.
Calculate enthalpy change for chemical and physical processes.
Calculate internal energy of an ideal gas from temperature.
Calculate work done in isothermal, isobaric, and adiabatic processes.
Apply the first law to relate heat, work, and internal energy change.
Verify second law constraints and calculate entropy production.
Evaluate the Clausius inequality for thermodynamic cycles.
Look up and apply Maxwell thermodynamic relations between state variables.
Reference tool for phase diagrams of common substances.
Calculate refraction angles using Snell law of refraction.
Calculate the critical angle for total internal reflection.
Calculate the Brewster angle for polarization by reflection.
Calculate transmitted intensity through a polarizer using Malus law.
Solve the thin lens equation 1/f = 1/do + 1/di for any variable.
Solve the mirror equation for object distance, image distance, or focal length.
Calculate magnification from image and object distances or heights.
Calculate focal length from lens curvature and refractive index.
Calculate lens optical power in diopters from focal length.
Convert between focal length and diopter values for lenses.
Calculate minimum deviation angle of light through a prism.
Calculate diffraction angles for a grating with given line spacing.
Calculate diffraction minima for single slit experiments.
Calculate interference fringe positions for double slit experiments.
Calculate minimum resolvable angle using the Rayleigh criterion.
Calculate numerical aperture of optical fibers and lenses.
Calculate total signal loss in fiber optic cable runs.
Calculate signal attenuation in dB over distance and connectors.
Calculate chromatic and modal dispersion in optical fibers.
Calculate polarization angle and intensity after polarizing filters.
Calculate phase shift and output polarization of a quarter wave plate.
Calculate polarization rotation through a half wave plate.
Calculate optical path length through media with varying refractive index.
Calculate temporal and spatial coherence length of a light source.
Calculate fringe spacing and visibility in interference patterns.
Reference guide to cell organelles, their structures, and functions.
Reference for DNA base pairing rules, complementary strands, and structure.
Reference guide to mRNA, tRNA, rRNA, and other RNA types and their roles.
Reference for primary, secondary, tertiary, and quaternary protein structures.
Reference guide to the six major enzyme classes and their reactions.
Comprehensive list of human hormones, their glands, and target organs.
Reference for major neurotransmitters, their functions, and pathways.
Reference guide to blood cells, plasma, and coagulation factors.
Reference for immune cell types including T cells, B cells, and macrophages.
Reference guide to major human organs and their primary functions.
Reference for digestive system organs, enzymes, and nutrient absorption.
Reference guide to respiratory anatomy, gas exchange, and lung volumes.
Reference for heart anatomy, blood vessels, and circulation pathways.
Reference guide to central and peripheral nervous system structures.
Reference for endocrine glands, hormones, and feedback mechanisms.
Reference guide to muscle types, major muscle groups, and actions.
Reference for bones, joints, and the axial and appendicular skeleton.
Reference guide to kidney anatomy, nephron function, and urine formation.
Reference for male and female reproductive anatomy and physiology.
Reference guide to lymph nodes, vessels, and immune tissue distribution.
Reference for skin layers, hair, nails, and associated glands.
Reference guide to eyes, ears, nose, tongue, and skin sensory receptors.
Reference for the 12 cranial nerves, their functions, and pathways.
Reference guide to 31 pairs of spinal nerves and their distributions.
Reference for dermatome maps and spinal nerve sensory distributions.
Complete reference of all world country capitals and their populations.
Reference for all 50 US state capitals with locations and details.
Reference guide to all European country capitals and key facts.
Reference for all Asian country capitals with population data.
Reference guide to all African country capitals and key statistics.
Reference for all South American country capitals and details.
Reference guide to Oceania and Pacific island nation capitals.
Reference for world country populations ranked and sortable.
Reference for country land areas ranked from largest to smallest.
Reference guide to the largest cities in the world by population.
Reference for the tallest mountains on each continent and globally.
Reference guide to the longest rivers in the world with length data.
Reference for the largest lakes by area and volume worldwide.
Reference guide to ocean depths, trenches, and underwater features.
Reference for the tallest waterfalls in the world with height data.
Reference guide to the largest deserts ranked by area worldwide.
Reference for the largest islands in the world ranked by area.
Reference guide to the smallest countries by area and population.
Reference for the most spoken languages by native and total speakers.
Reference guide to critically endangered species and conservation status.
Reference for world time zones, UTC offsets, and DST rules.
Reference guide to climate classification zones and their characteristics.
Reference for world biomes including tundra, desert, forest, and grassland.
Reference guide to major and minor tectonic plates and boundaries.
Reference for major ocean currents, gyres, and thermohaline circulation.
Reference guide to major ancient civilizations and their contributions.
Timeline reference for key events of World War I and World War II.
Reference for major Cold War events, crises, and proxy conflicts.
Timeline of key milestones in the US-Soviet space race.
Reference guide to key inventions and events of the Industrial Revolution.
Timeline reference for major events of the French Revolution.
Reference for key battles, events, and figures of the American Revolution.
Timeline of the Roman Empire from founding to fall of the West.
Reference for ancient Greek history, city-states, and key events.
Reference guide to ancient Egyptian dynasties, pharaohs, and monuments.
Reference for Chinese dynastic history from Xia to Qing.
Reference guide to Japanese historical periods from Jomon to modern.
Timeline of key events during the European Middle Ages.
Timeline reference for the European Renaissance and its key figures.
Reference for major voyages, explorers, and discoveries of the Age of Exploration.
Reference guide to European colonial empires and their territories.
Reference for notable world leaders throughout history by region.
Reference guide to major peace treaties and their terms throughout history.
Timeline of major inventions from ancient times to the modern era.
Reference for landmark scientific discoveries and their discoverers.
Reference guide to Nobel Prize laureates by category and year.
Reference for Olympic Games history, host cities, and notable events.
Reference guide to UNESCO World Heritage Sites by country and type.
Reference for historically significant battles and their outcomes.
Reference for the largest empires in history ranked by territory.
Comprehensive reference for formal and informal logical fallacies with examples.
Reference guide for cognitive biases organized by decision, social, and memory categories.
Reference for mental models used in decision-making, problem-solving, and strategy.
Reference for major philosophical schools: Stoicism, Existentialism, Pragmatism, and more.
Reference for ethical frameworks: utilitarianism, deontology, virtue ethics, and care.
Collection of famous thought experiments: trolley problem, Chinese room, and more.
Check the validity of categorical syllogisms using Aristotelian logic rules.
Generate truth tables for propositional logic expressions with AND, OR, NOT, and IF.
Reference for Boolean algebra laws, theorems, and simplification techniques.
Reference for propositional logic connectives, inference rules, and proofs.
Reference for predicate logic: quantifiers, variables, and proof strategies.
Reference for modal logic: necessity, possibility, and possible worlds semantics.
Reference for fuzzy logic: membership functions, operators, and applications.
Reference for set theory: operations, axioms, Venn diagrams, and cardinality.
Generate Venn diagrams for 2, 3, or 4 sets with intersection labeling.
Solve and simplify Boolean expressions using 2, 3, or 4-variable Karnaugh maps.
Generate weighted decision matrices to compare options across multiple criteria.
Generate structured SWOT analysis templates for strategic planning.
Reference and template for PESTLE analysis: Political, Economic, Social, Tech, Legal, Env.
Reference for Porter's Five Forces framework for industry competitive analysis.
Reference for the BCG growth-share matrix: Stars, Cash Cows, Dogs, and Question Marks.
Reference for the Ansoff growth matrix: penetration, development, diversification.
Reference for Porter's value chain analysis: primary and support activities.
Generate Lean Canvas templates for startup business model planning.
Generate Business Model Canvas templates with all nine building blocks.
Calculate your household carbon footprint from energy, heating, and appliance usage.
Calculate carbon emissions from flights, driving, trains, and other transport modes.
Calculate the carbon footprint of your diet based on food categories and consumption.
Calculate your personal water footprint from daily activities and food choices.
Estimate your ecological footprint in global hectares from lifestyle choices.
Track and analyze household energy consumption patterns by appliance and season.
Reference guide for renewable energy sources: solar, wind, hydro, and geothermal.
Calculate solar panel investment payback period from cost, output, and electricity rates.
Estimate wind power generation potential from wind speed, altitude, and turbine specs.
Reference guide for geothermal energy: heat pumps, power plants, and applications.
Reference guide for hydropower: dam types, turbines, and environmental impact.
Reference guide for biomass energy: feedstocks, conversion processes, and efficiency.
Reference guide for tidal energy: barrage, stream, and range technologies.
Reference guide for wave energy conversion technologies and global potential.
Reference guide for nuclear energy: fission, fusion, reactor types, and safety.
Reference guide for fossil fuels: coal, oil, natural gas, and emissions data.
Reference for greenhouse gases: CO2, methane, N2O, and their warming potentials.
Reference guide for global warming science, temperature trends, and projections.
Reference for sea level rise data, projections, and coastal impact assessments.
Reference for global deforestation rates, causes, and reforestation efforts.
Reference for plastic pollution statistics, ocean gyres, and reduction strategies.
Reference for air quality indices, pollutant types, and health impact levels.
Reference for water quality parameters: pH, turbidity, dissolved oxygen, and standards.
Reference for soil health indicators: pH, organic matter, texture, and nutrients.
Reference for biodiversity loss statistics, endangered species, and conservation efforts.
Reference guide for major personality type systems and their classifications.
Reference for all 16 Myers-Briggs personality types with traits and functions.
Reference for the OCEAN model: Openness, Conscientiousness, Extraversion, Agreeableness, Neuroticism.
Reference for the nine Enneagram personality types, wings, and growth paths.
Reference for DISC behavioral model: Dominance, Influence, Steadiness, Conscientiousness.
Reference for attachment theory styles: secure, anxious, avoidant, and disorganized.
Reference for the five love languages: words, acts, gifts, time, and touch.
Reference for psychological defense mechanisms: denial, projection, sublimation, and more.
Reference for grief models including denial, anger, bargaining, depression, and acceptance.
Reference for Maslow hierarchy: physiological, safety, love, esteem, and self-actualization.
Reference for Erikson eight psychosocial development stages from infancy to old age.
Reference for Piaget four stages of cognitive development in children.
Reference for Kohlberg six stages of moral development across three levels.
Reference for learning style models: visual, auditory, kinesthetic, and reading.
Reference for Gardner eight intelligences: linguistic, logical, spatial, musical, and more.
Reference for emotional intelligence components: self-awareness, empathy, and regulation.
Reference for growth vs fixed mindset concepts and strategies for development.
Reference for cognitive development milestones across the lifespan.
Reference for memory techniques: spaced repetition, mnemonics, method of loci, and chunking.
Reference for effective study methods: Pomodoro, Feynman technique, active recall, and more.
Reference for stress management techniques: breathing, exercise, and time management.
Reference guide for mindfulness practices, body scan, and present-moment awareness.
Reference for meditation types: focused attention, open monitoring, transcendental, and zen.
Reference for therapy approaches: CBT, DBT, psychodynamic, humanistic, and EMDR.
Reference for healthy coping strategies: problem-focused, emotion-focused, and adaptive.
Reference for the digits of pi with history, properties, and computation records.
Reference for the digits of Euler number e with properties and series representations.
Reference for the golden ratio phi with digits, properties, and appearances in nature.
Reference for the Euler-Mascheroni constant gamma with digits and properties.
Reference for the Catalan constant with digits, series, and integral representations.
Reference for Apery constant zeta(3) with proof of irrationality and series formulas.
Reference for the Khinchin constant from continued fraction theory with digits.
Reference for Feigenbaum constants in chaos theory and period-doubling bifurcation.
Reference for the plastic number with minimal polynomial and architectural applications.
Reference for the silver ratio with continued fraction and geometric properties.
Reference for area formulas of all common shapes: circle, triangle, polygon, and ellipse.
Reference for volume formulas of 3D shapes: sphere, cylinder, cone, and prism.
Reference for surface area formulas of 3D solids including composite shapes.
Reference for perimeter and circumference formulas of all common shapes.
Reference for trigonometric identities, sum/difference, double/half angle formulas.
Reference for common derivative rules: power, chain, product, quotient, and trig.
Reference for common integral formulas: basic, trigonometric, exponential, and rational.
Reference for common series: arithmetic, geometric, Taylor, Maclaurin, and Fourier.
Reference for probability formulas: Bayes theorem, combinations, permutations, and distributions.
Reference for statistics formulas: mean, variance, standard deviation, and regression.
Reference for logarithm properties: product, quotient, power, change of base rules.
Reference for exponent laws: product, quotient, power, zero, and negative exponents.
Reference for radical and root rules: simplification, rationalization, and operations.
Reference for inequality properties, solving techniques, and interval notation.
Reference for absolute value properties, equations, and inequality solving methods.
Reference for the fastest animals on land, sea, and air with speed records.
Reference for the slowest animals with movement speeds and survival adaptations.
Reference for the tallest animals with height measurements and size comparisons.
Reference for the heaviest animals on Earth with weight records across species.
Reference for the smallest animals by class with size measurements.
Reference for the longest-lived animals with lifespan records and aging biology.
Reference for deepest-diving animals with depth records and pressure adaptations.
Reference for the fastest birds in flight, dive, and on land with speed records.
Reference for the fastest fish species with swimming speed records.
Reference for the most venomous animals ranked by toxicity and danger level.
Reference for the tallest buildings and structures in the world with height data.
Reference for the longest bridges by span length, total length, and type.
Reference for the deepest caves in the world with depth records and exploration history.
Reference for the largest known meteorites with mass, location, and impact data.
Reference for the fastest trains and rail systems with speed records worldwide.
Reference for the fastest aircraft with speed records from propeller to hypersonic.
Reference for the fastest production and land speed record cars with top speeds.
Reference for the largest ships by displacement, length, and vessel type.
Reference for the largest aircraft by wingspan, length, and payload capacity.
Reference for the tallest trees by species with height records and locations.
Reference for the oldest trees and organisms with age records and dating methods.
Reference for the largest flowers and inflorescences with size records.
Reference for the hottest recorded temperatures and consistently hot locations.
Reference for the coldest recorded temperatures and consistently cold locations.
Reference for the driest locations on Earth with rainfall records and desert data.
Guide to baking: oven temperatures, convection vs conventional, and baking tips.
Guide to roasting: temperatures, timing charts, and techniques for meat and vegetables.
Guide to grilling: direct vs indirect heat, charcoal vs gas, and temperature zones.
Guide to broiling: rack positions, timing, and suitable foods for top-down heat.
Guide to sauteing: pan selection, oil smoke points, and proper technique.
Guide to pan frying: oil depth, temperature control, and breading techniques.
Guide to deep frying: oil selection, temperature ranges, and safety practices.
Guide to steaming: equipment types, timing charts, and nutrient retention benefits.
Guide to boiling: rolling boil vs simmer, altitude adjustments, and blanching.
Guide to poaching: temperature control, suitable liquids, and poaching eggs and fish.
Guide to braising: liquid ratios, suitable cuts, and low-slow cooking techniques.
Guide to stewing: ingredient ratios, thickening methods, and flavor development.
Guide to blanching: water vs oil blanching, ice bath technique, and timing charts.
Guide to searing: Maillard reaction, pan temperature, and reverse sear technique.
Guide to food smoking: hot vs cold smoking, wood types, and temperature control.
Guide to curing: salt curing, sugar curing, nitrates, and food preservation safety.
Guide to pickling: vinegar ratios, fermentation pickling, and canning safety.
Guide to fermentation: lacto-fermentation, kombucha, kimchi, and sauerkraut basics.
Guide to food dehydration: temperature settings, timing, and storage methods.
Guide to freeze drying: process overview, equipment, and shelf-life comparison.
Guide to sous vide: time-temperature charts, equipment, and finishing techniques.
Guide to pressure cooking: PSI levels, timing adjustments, and safety features.
Guide to slow cooking: low vs high settings, liquid ratios, and recipe adaptation.
Guide to air frying: temperature conversion from deep frying, timing, and best foods.
Guide to wok cooking: seasoning, wok hei technique, and stir-fry fundamentals.
Reference for the United States: geography, population, economy, and key facts.
Reference for the United Kingdom: geography, population, economy, and key facts.
Reference for France: geography, population, economy, and key facts.
Reference for Germany: geography, population, economy, and key facts.
Reference for Japan: geography, population, economy, and key facts.
Reference for China: geography, population, economy, and key facts.
Reference for India: geography, population, economy, and key facts.
Reference for Brazil: geography, population, economy, and key facts.
Reference for Australia: geography, population, economy, and key facts.
Reference for Canada: geography, population, economy, and key facts.
Reference for Italy: geography, population, economy, and key facts.
Reference for Spain: geography, population, economy, and key facts.
Reference for Mexico: geography, population, economy, and key facts.
Reference for South Korea: geography, population, economy, and key facts.
Reference for Russia: geography, population, economy, and key facts.
Reference for Turkey: geography, population, economy, and key facts.
Reference for Saudi Arabia: geography, population, economy, and key facts.
Reference for the United Arab Emirates: geography, population, economy, and key facts.
Reference for Singapore: geography, population, economy, and key facts.
Reference for Switzerland: geography, population, economy, and key facts.
Reference for the Netherlands: geography, population, economy, and key facts.
Reference for Sweden: geography, population, economy, and key facts.
Reference for Norway: geography, population, economy, and key facts.
Reference for Denmark: geography, population, economy, and key facts.
Reference for Finland: geography, population, economy, and key facts.
Reference for the metric (SI) system: base units, prefixes, and conversion factors.
Reference for the British Imperial system: length, weight, and volume units.
Reference for US customary units and differences from the Imperial system.
Reference for troy weight system used in precious metals: grains, pennyweights, ounces.
Reference for the apothecary weight system: scruples, drams, and ounces.
Reference for avoirdupois weight system: ounces, pounds, stones, and tons.
Reference for nautical measurement units: knots, nautical miles, fathoms, and cables.
Reference for astronomical distance units: AU, light-year, parsec, and kiloparsec.
Reference for Planck natural units: length, time, mass, temperature, and charge.
Reference for the centimetre-gram-second system and its electromagnetic variants.
Reference for the metre-kilogram-second system and its relation to SI.
Reference for the foot-pound-second system used in engineering calculations.
Reference for all SI prefixes from quecto to quetta with symbols and values.
Reference for IEC binary prefixes: kibi, mebi, gibi, tebi, and their SI equivalents.
Reference for paper size standards: A-series, B-series, C-series, and US letter/legal.
Reference for AWG, SWG, and metric wire gauge systems with diameter tables.
Reference for screw size standards: UNC, UNF, metric, and self-tapping sizes.
Reference for pipe sizing standards: NPS, DN, schedule numbers, and wall thickness.
Reference for nominal vs actual lumber dimensions and common board sizes.
Reference for concrete grades, mix ratios, compressive strength, and applications.
Reference for steel grades: AISI, SAE, and EN standards with composition data.
Reference for wood grading standards: hardwood, softwood, and plywood grades.
Reference for math symbols: operators, relations, sets, logic, and Greek letters.
Reference for counting systems: base-10, base-12, base-20, and base-60 systems.
Reference for Roman numerals: I to MMMCMXCIX with rules and modern usage.
Reference for Babylonian numerals: base-60 cuneiform system and conversion.
Live 7-day weather forecast for any city. Powered by Open-Meteo (no API key needed). Temperature, humidity, wind, precipitation.
Live AQI for any city — PM2.5, PM10, NO₂, O₃, SO₂, CO. Powered by Open-Meteo Air-Quality.
Sunrise, sunset, twilight phases, day length for any city and date. Free sunrise-sunset.org API.
NASA Astronomy Picture of the Day with full explanation. Pick any date.
Images, PDFs, video, audio, text, code, calculators, SEO, and more. All free, all in your browser.
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