Quick Convert
| US/CA | UK/AU | EU | Japan | Diam (mm) | Circ (mm) |
|---|---|---|---|---|---|
| 3 | F | 44 | 4 | 14.1 | 44.2 |
| 3.5 | G | 45.5 | 5 | 14.5 | 45.5 |
| 4 | H | 46.5 | 7 | 14.9 | 46.8 |
| 4.5 | I | 47.8 | 8 | 15.3 | 48 |
| 5 | J | 49 | 9 | 15.7 | 49.3 |
| 5.5 | K | 50.3 | 10 | 16.1 | 50.6 |
| 6 | L | 51.5 | 11 | 16.5 | 51.8 |
| 6.5 | M | 52.8 | 12 | 16.9 | 53.1 |
| 7 | N | 54 | 13 | 17.3 | 54.4 |
| 7.5 | O | 55.3 | 14 | 17.7 | 55.6 |
| 8 | P | 56.5 | 15 | 18.1 | 56.9 |
| 8.5 | Q | 57.8 | 16 | 18.5 | 58.1 |
| 9 | R | 59 | 17 | 18.9 | 59.3 |
| 9.5 | S | 60.3 | 18 | 19.4 | 60.6 |
| 10 | T | 61.5 | 19 | 19.8 | 62.1 |
| 10.5 | U | 62.8 | 20 | 20.2 | 63.4 |
| 11 | V | 64 | 22 | 20.6 | 64.6 |
| 11.5 | W | 65.3 | 23 | 21 | 65.9 |
| 12 | X | 66.5 | 24 | 21.4 | 67.2 |
| 13 | Z | 69 | 26 | 22.2 | 69.7 |
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About Ring Size
Most online tools for this task bury what you need behind ads and forms. Ring Size takes the opposite approach: load the page, do the job, leave. Everything happens client-side, which means your files and data never leave your machine. The interface is intentionally minimal so you can focus on the task instead of learning the tool. It is one of about a hundred utility tools that share the same philosophy: do one thing, do it well, get out of your way.
When you'd reach for Ring Size
You're cleaning up a folder of files that accumulated over a project and need to standardize them.
Designers, writers, and developers wrapping up deliverables.
Drop each file in, copy the output, move on.
You're on a public or shared machine and don't want to leave traces of what you're working on.
Travelers, contractors, anyone working from a friend's computer.
Nothing is uploaded, nothing persists if you're not signed in.
You need to handle a one-off task right before a meeting and don't have time to install anything.
Anyone working remotely on a borrowed or restricted machine.
Open the page, get the result, paste it into your doc — under a minute.
You're hitting the daily limit of a paid SaaS and need a backup option for a single quick job.
Marketers and ops people whose primary tool is metered.
Stay productive without burning credits.
Frequently asked about Ring Size
- Can I use Ring Size commercially?
- Yes. The output of Ring Size belongs entirely to you, with no licensing restrictions.
- Are my files uploaded to a server when I use Ring Size?
- Ring Size processes everything in your browser using local APIs. Your files never leave your device.
- Do I need to create an account to use Ring Size?
- No. Ring Size works without any signup. We only ask for an email if you decide to subscribe to a paid plan.
- Does Ring Size work on mobile?
- Yes, Ring Size is fully responsive and tested on iOS Safari and Android Chrome.
- Is Ring Size really free?
- Yes — Ring Size is free for unlimited personal use, with no account required and no watermark on the output.