Convert UK men's ring sizes to US, EU, India, Japan, Australia, Switzerland, China and more — with full inner diameter and circumference reference for every size from A to Z+6
Letter-based: A to Z+6. Each half-letter = ~0.4 mm diameter increase. Average man = S or T. Also used in Australia and South Africa.
Average: S–TNumeric ¼-size increments. No direct formula to UK letters — always convert via circumference. Average man = US 9–10. Also used in Mexico.
Average: US 9–9.25Inner circumference in mm, rounded to nearest whole number. EU 56 = 56 mm circumference. Used across France, Germany, Italy, Spain, Scandinavia.
Average: EU 56–57Numeric scale 1–32 based on inner circumference. Offset from EU by approximately −10 at men's average sizes. Common at Indian jewellers worldwide.
Average: IN 19–20Numeric 1–32 scale. Japan and China share almost identical sizing based on inner circumference in mm. Used across East and Southeast Asia.
Average: JP/CN 16–17Uses the same letter system as the UK but with a ½-size offset at some sizes. Broadly interchangeable with UK for most practical purchases.
Average: AU S–TUses EU circumference minus 40. So EU 56 = Swiss 16, EU 57 = Swiss 17. Simple subtraction once you know the EU size.
Average: Swiss 16–17France uses inner diameter in mm (so 17.9 mm = French 18). Russia uses the same diameter-based system. Both differ significantly from EU circumference.
Average: FR/RU 18| 🇬🇧 UK | ⌀ mm | Circ. mm | 🇺🇸 US | 🇪🇺 EU | 🇮🇳 India | 🇯🇵 Japan | 🇨🇳 China | 🇦🇺 AU | 🇨🇭 Swiss | 🇫🇷 France | Category |
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Enter your measurement OR your known size in one system — get all 8 equivalents instantly
Never add a fixed number to convert UK to US — the relationship between UK letters and US numbers is not linear. A size conversion table or the calculator above is the only reliable method.
EU size = inner circumference in mm — this makes EU the easiest system to understand. If you know your EU size, your circumference in mm is the same number. EU 57 = 57 mm inner circumference.
Swiss size = EU size minus 40 — the simplest conversion relationship in global ring sizing. EU 56 → Swiss 16. EU 63 → Swiss 23.
French/Russian size = inner diameter in mm, rounded — measure diameter with calipers. 17.9 mm diameter = French 18. 18.2 mm = French 18. Rounds to nearest whole mm.
Measure in the evening at room temperature — fingers are larger in the evening and in warm conditions. Cold weather can reduce finger size by a full UK size, which throws off all conversions.
Indian jewellers may use their own scale — while the BIS numeric scale (1–32) is standard, some Indian jewellers use their own regional sequences. Always confirm with the specific retailer before ordering.
Australian sizes broadly match UK but with minor offsets — for most men's sizes (R–Z), UK and Australian sizes are the same letter. At the extremes (below L or above Z) there can be a half-size discrepancy.