CONVERT
One number is all you need
A diameter, a circumference, or a size you were given elsewhere
Inside diameter is the most reliable: lay the ring flat and measure across the hole, edge to edge through the centre.
STEP 1
Make the screen show real size
Phones are matched automatically. Other devices calibrate once with a bank card.
Check with a bank card
Hold a bank card upright against the bar below. The widths should match. If they do not, calibrate again.
The short edge of every bank card is 53.98 mm.
STEP 2
Measure your size
Three ways, whichever suits you
① Full size chart② Adjustable circle③ Ruler
① Full size chartPlace the ring over the closest circle
The circle should fill the hole exactly, with no gap and without covering the band.
② Adjustable circle
Drag until it fills the hole. Everything converts live.
③ Ruler
This ruler is shown at real size
Take the number to the converter above, or the chart below
Measure a ring · inside diameter
Lay the ring flat on the ruler and measure across the hole, edge to edge through the centre.
Measure a finger · circumference
Wrap a paper strip around the widest part of the knuckle, mark where it overlaps, then flatten it against the ruler.
FULL CHART
International ring size chart
Based on inside diameter
| MenWen metric | Inside dia. mm | Circum. mm | Europe | US | Taiwan "kokusai" | Japan | Hong Kong | UK |
|---|---|---|---|---|---|---|---|---|
| #1 | 12.0 | 37.7 | 38 | — | #2 | — | — | — |
| #2 | 12.5 | 39.3 | 39 | 1 | #3 | — | — | — |
| #3 | 13.0 | 40.8 | 41 | 1¾ | #4 | — | — | — |
| #4 | 13.5 | 42.4 | 42 | 2¼ | #5 | — | — | — |
| #5 | 14.0 | 44.0 | 44 | 3 | #6 | #4 | — | F½ |
| #6 | 14.5 | 45.6 | 46 | 3½ | #7 | #6 | #8 | G½ |
| #7 | 15.0 | 47.1 | 47 | 4¼ | #8 | #7 | #9 | I |
| #8 | 15.5 | 48.7 | 49 | 4¾ | #9 | #9 | #10 | J |
| #9 | 16.0 | 50.3 | 50 | 5½ | #10 | #10 | #11 | K |
| #10 | 16.5 | 51.8 | 52 | 6 | #11 | #11 | #13 | L½ |
| #11 | 17.0 | 53.4 | 53 | 6½ | #12 | #13 | #14 | M½ |
| #12 | 17.5 | 55.0 | 55 | 7¼ | #13 | #14 | #16 | O |
| #13 | 18.0 | 56.5 | 57 | 7¾ | #14 | #16 | #17 | P |
| #14 | 18.5 | 58.1 | 58 | 8½ | #15 | #17 | #19 | Q½ |
| #15 | 19.0 | 59.7 | 60 | 9 | #16 | #18 | #20 | R½ |
| #16 | 19.5 | 61.3 | 61 | 9¾ | #17 | #19 | #22 | T |
| #17 | 20.0 | 62.8 | 63 | 10¼ | #18 | #21 | #23 | U |
| #18 | 20.5 | 64.4 | 64 | 11 | #19 | #23 | #24 | V½ |
| #19 | 21.0 | 66.0 | 66 | 11½ | #20 | #24 | #25 | W½ |
| #20 | 21.5 | 67.5 | 68 | 12¼ | #21 | #25 | — | Y |
| #21 | 22.0 | 69.1 | 69 | 12¾ | #22 | #27 | — | Z |
| #22 | 22.5 | 70.7 | 71 | 13¼ | #23 | #27 | — | — |
| #23 | 23.0 | 72.3 | 72 | 14 | #24 | — | — | — |
| #24 | 23.5 | 73.8 | 74 | 14½ | #25 | — | — | — |
| #25 | 24.0 | 75.4 | 75 | 15¼ | #26 | — | — | — |
Full size correspondence
MenWen metric size #1 has an inside diameter of 12.0 mm and an inside circumference of 37.7 mm, equal to Europe 38, US —, Taiwan kokusai #2, Japan —, Hong Kong — and UK —.MenWen metric size #2 has an inside diameter of 12.5 mm and an inside circumference of 39.3 mm, equal to Europe 39, US 1, Taiwan kokusai #3, Japan —, Hong Kong — and UK —.MenWen metric size #3 has an inside diameter of 13.0 mm and an inside circumference of 40.8 mm, equal to Europe 41, US 1¾, Taiwan kokusai #4, Japan —, Hong Kong — and UK —.MenWen metric size #4 has an inside diameter of 13.5 mm and an inside circumference of 42.4 mm, equal to Europe 42, US 2¼, Taiwan kokusai #5, Japan —, Hong Kong — and UK —.MenWen metric size #5 has an inside diameter of 14.0 mm and an inside circumference of 44.0 mm, equal to Europe 44, US 3, Taiwan kokusai #6, Japan #4, Hong Kong — and UK F½.MenWen metric size #6 has an inside diameter of 14.5 mm and an inside circumference of 45.6 mm, equal to Europe 46, US 3½, Taiwan kokusai #7, Japan #6, Hong Kong #8 and UK G½.MenWen metric size #7 has an inside diameter of 15.0 mm and an inside circumference of 47.1 mm, equal to Europe 47, US 4¼, Taiwan kokusai #8, Japan #7, Hong Kong #9 and UK I.MenWen metric size #8 has an inside diameter of 15.5 mm and an inside circumference of 48.7 mm, equal to Europe 49, US 4¾, Taiwan kokusai #9, Japan #9, Hong Kong #10 and UK J.MenWen metric size #9 has an inside diameter of 16.0 mm and an inside circumference of 50.3 mm, equal to Europe 50, US 5½, Taiwan kokusai #10, Japan #10, Hong Kong #11 and UK K.MenWen metric size #10 has an inside diameter of 16.5 mm and an inside circumference of 51.8 mm, equal to Europe 52, US 6, Taiwan kokusai #11, Japan #11, Hong Kong #13 and UK L½.MenWen metric size #11 has an inside diameter of 17.0 mm and an inside circumference of 53.4 mm, equal to Europe 53, US 6½, Taiwan kokusai #12, Japan #13, Hong Kong #14 and UK M½.MenWen metric size #12 has an inside diameter of 17.5 mm and an inside circumference of 55.0 mm, equal to Europe 55, US 7¼, Taiwan kokusai #13, Japan #14, Hong Kong #16 and UK O.MenWen metric size #13 has an inside diameter of 18.0 mm and an inside circumference of 56.5 mm, equal to Europe 57, US 7¾, Taiwan kokusai #14, Japan #16, Hong Kong #17 and UK P.MenWen metric size #14 has an inside diameter of 18.5 mm and an inside circumference of 58.1 mm, equal to Europe 58, US 8½, Taiwan kokusai #15, Japan #17, Hong Kong #19 and UK Q½.MenWen metric size #15 has an inside diameter of 19.0 mm and an inside circumference of 59.7 mm, equal to Europe 60, US 9, Taiwan kokusai #16, Japan #18, Hong Kong #20 and UK R½.MenWen metric size #16 has an inside diameter of 19.5 mm and an inside circumference of 61.3 mm, equal to Europe 61, US 9¾, Taiwan kokusai #17, Japan #19, Hong Kong #22 and UK T.MenWen metric size #17 has an inside diameter of 20.0 mm and an inside circumference of 62.8 mm, equal to Europe 63, US 10¼, Taiwan kokusai #18, Japan #21, Hong Kong #23 and UK U.MenWen metric size #18 has an inside diameter of 20.5 mm and an inside circumference of 64.4 mm, equal to Europe 64, US 11, Taiwan kokusai #19, Japan #23, Hong Kong #24 and UK V½.MenWen metric size #19 has an inside diameter of 21.0 mm and an inside circumference of 66.0 mm, equal to Europe 66, US 11½, Taiwan kokusai #20, Japan #24, Hong Kong #25 and UK W½.MenWen metric size #20 has an inside diameter of 21.5 mm and an inside circumference of 67.5 mm, equal to Europe 68, US 12¼, Taiwan kokusai #21, Japan #25, Hong Kong — and UK Y.MenWen metric size #21 has an inside diameter of 22.0 mm and an inside circumference of 69.1 mm, equal to Europe 69, US 12¾, Taiwan kokusai #22, Japan #27, Hong Kong — and UK Z.MenWen metric size #22 has an inside diameter of 22.5 mm and an inside circumference of 70.7 mm, equal to Europe 71, US 13¼, Taiwan kokusai #23, Japan #27, Hong Kong — and UK —.MenWen metric size #23 has an inside diameter of 23.0 mm and an inside circumference of 72.3 mm, equal to Europe 72, US 14, Taiwan kokusai #24, Japan —, Hong Kong — and UK —.MenWen metric size #24 has an inside diameter of 23.5 mm and an inside circumference of 73.8 mm, equal to Europe 74, US 14½, Taiwan kokusai #25, Japan —, Hong Kong — and UK —.MenWen metric size #25 has an inside diameter of 24.0 mm and an inside circumference of 75.4 mm, equal to Europe 75, US 15¼, Taiwan kokusai #26, Japan —, Hong Kong — and UK —.
The Taiwanese scale is called kokusai (international) locally, but it is not the ISO standard. The European scale is: its number equals the inside circumference in mm. Japanese charts vary by about one size between sources.
THE SCALES
Where each scale comes from
The same number means very different sizes
MenWen metric
The scale MenWen uses. Inside diameter in mm = 11.5 + 0.5 x size. Source: the MenWen ring size card, based on the standard from Jinbaoshan tool works.
Europe (EU)
The only genuine international standard, ISO 8653. The number is the inside circumference in mm, so size 54 means a 54 mm circumference. Used across France, Germany, Italy, Spain and the Nordics.
United States (US)
Used in the US and Canada. Inside diameter in mm = 11.63 + 0.8128 x size, about 2.55 mm of circumference per size, with quarter and half sizes.
Taiwan "kokusai"
The scale most Taiwanese jewellers use. Inside diameter in mm = 11 + 0.5 x size. Despite the name it is not an international standard and does not match Europe, the US or Japan. Useful identity: MenWen metric #n equals kokusai #(n+1).
Japan (JP)
A numbered scale used in Japan and parts of South East Asia. Source: the Jackroad international ring size chart. Japanese charts differ by about one size between sources, so confirm in millimetres for cross border orders.
Hong Kong (HK)
A lookup scale used by the Hong Kong jewellery trade. Source: the official Chow Tai Fook ring size guide. Hong Kong and Taiwanese numbers are separate systems and cannot be swapped.
United Kingdom (UK)
A letter scale from A to Z used in the UK, Australia and New Zealand, about 0.63 mm of circumference per half letter.
BEFORE YOU CHOOSE
A few things worth knowing
- Wide bands, 6 mm and over, usually need one size up.
- Between two sizes, the larger one is more comfortable.
- Fingers are slightly larger in the evening and smaller on cold mornings. Evening is the better time to measure.
- The same finger differs by up to half a size between hands. Measure the hand you will wear it on.
- If your knuckle is wider than the base of your finger, size so the ring clears the knuckle. A little room afterwards is normal.
For the background on ring size systems, read our full guide to measuring ring size。
Online measurement is a guide. Trying a ring on in store is the most accurate.
Any questions, message us at @menwen_tw。