Your size
Range
A general guideline only — ring sizes vary by maker. If you measured the inside of an existing ring, use the inner-diameter (mm) column; if you measured around your finger with thread or a sizer, use the EU / circumference (mm) column. A Japanese size number means the same regardless of gender — the ranges just differ by what people usually wear.
Conversion chart
Your row is highlighted. Click any cell to copy it.
What Japanese size (go) is a US 6 ring you found overseas? You secretly measured a ring and it's about 16 mm inside — which size is that? You measured your finger's circumference with a sizer and want the matching size? Ring sizes come in Japanese go numbers, US, UK, and EU (circumference in mm), and looking up each one every time is a chore. This ring size converter lines up Japanese go, US, UK, EU (circumference mm), and inner diameter (mm) in one chart. Choose a range (women's 1–20 or men's 10–27), then pick which system and value your size is in, and the corresponding row — the set of sizes considered equivalent — is highlighted across every column so you can compare all the notations and the real measurements at a glance. Every cell can be clicked to copy, so you can paste it straight into a checkout form or a note. Ring sizes are based on finger thickness, so the most reliable approach is matching by real measurement: if you measured the inside diameter of an existing ring with calipers, use the inner-diameter (mm) column; if you measured around your finger with thread or a ring sizer, use the EU / circumference (mm) column. A go number means the same regardless of gender — women's and men's here just narrow the range people usually wear. Note that US/UK mappings vary by maker and chart, so this is a general guideline. Nothing you select is ever sent to a server; everything runs entirely inside your browser.
How to use
- Choose a range: women's (1–20) or men's (10–27).
- Pick the system your size is in: Japan (go), US, UK, or EU circumference (mm).
- Select the value, and the matching row is highlighted so you can compare every notation and the inner diameter (mm). Click any cell to copy it.
FAQ
Is anything I select sent to a server?
No. The size lookup runs entirely inside your browser; nothing you select is uploaded, stored, or transmitted. It works fully locally.
How do I measure my ring size?
Two ways. (1) Wrap a thin strip of paper or thread around the finger to measure its circumference in mm, then match the 'EU / circumference (mm)' column. (2) If you have a ring that fits, measure its inside diameter (mm) with calipers and match the 'Inner diameter (mm)' column. Measure later in the day, when fingers are slightly larger, for a safer fit.
What Japanese size is a US 6 ring?
As a general guideline, a US 6 is roughly a Japanese size 11 (inner diameter about 16.4 mm, circumference about 51.5 mm, UK M). Maker variation exists, so confirm with the diameter or circumference when you can.
What size is a 16 mm inner diameter?
An inner diameter of about 16.0 mm is a Japanese size 10 (US 5.5, UK L, circumference about 50.3 mm). Measure the inside diameter of a ring that fits with calipers and match it to the 'Inner diameter (mm)' column to read off the size.
How accurate is this conversion chart?
The physical values (inner diameter and EU circumference) follow standard correspondences. The US/UK mappings, however, vary by maker and chart, so treat them as a guideline. For the final decision, base it on your finger's measured circumference or the inner diameter of a ring that fits.
Do women's and men's go numbers mean different things?
No. A go number means the same for everyone — the same number is the same circumference. The women's (1–20) and men's (10–27) ranges here only narrow the chart to the sizes people usually wear, and overlapping sizes convert identically in both.