Converter
Ring size converter
One size in, one size out — with the millimetres that justify it. Choose a source system and size, choose a target system, and read the diameter and circumference alongside the label, so you can check the answer instead of trusting it blindly.
Ring size converter
How conversion works here — and where it stops
Source → millimetres
Every source resolves to a physical diameter first: US from its published ladder, EU as circumference ÷ π, India as (size + 40) ÷ π, UK from its letter ladder. No label is converted directly to another label.
Millimetres → target row
The target label is the nearest row in the same unified table the chart uses. That is what keeps the converter, the chart and the calculators consistent for the same measurement.
Outside the chart? No label.
EU 72, very small UK letters, and very large Indian sizes fall outside the US 3–13.5 range. For those, the converter still shows diameter and circumference — the numbers a seller can actually use — and says plainly that no chart row equivalent exists.
Conversion examples
US 7 → UK N (approx.)
Diameter 17.32 mm, circumference 54.4 mm, EU 54. On half-letter charts the same ring is N½ — that half-letter disagreement is documented on the UK page.
EU 52 → US 6
EU 52 means 52 mm around, so diameter is 52 ÷ π = 16.55 mm. The nearest chart row is US 6 (16.51 mm). The 0.04 mm gap is the EU rounding, not an error.
India 14 → US 7 (approx.)
India 14 means about 54 mm around (14 + 40), diameter 17.19 mm. Nearest row is US 7 (17.32 mm). Published Indian tables vary by ±1 here, so this is approximate.
Related guides
- International ring size chart
The full table behind this converter, searchable and filterable.
- Ring size calculator
Start from a measurement instead of a size label.
- Measurement methodology
How the dataset is built, and what is not yet verified.