US sizes to diameter (mm)
Type a value in US to get it in ⌀ mm instantly.
17.32⌀ mm
That's 1.05× as big as an average women’s ring, while an average men’s ring is 1.1× bigger. That is about 17.32 mm across the inside.
Convert the other way: ⌀ mm to US
What it means
How big is that ring?
Measure a ring that fits across its inside, or wrap a strip of paper around the finger. Fingers swell in heat, so measure warm.
The math
How to convert US to ⌀ mm
Each scale steps differently: EU = circumference in mm, US = (circumference − 36.54) ÷ 2.55, and the diameter is the circumference divided by π.
Example: 7 US = 17.3197 ⌀ mm.
Every unit
Your ring size in every system
Tables
US to ⌀ mm conversion table
| US | ⌀ mm |
|---|---|
| 3 US | 14.0685 ⌀ mm |
| 4 US | 14.8813 ⌀ mm |
| 5 US | 15.6941 ⌀ mm |
| 6 US | 16.5069 ⌀ mm |
| 7 US | 17.3197 ⌀ mm |
| 8 US | 18.1325 ⌀ mm |
| 9 US | 18.9453 ⌀ mm |
| 10 US | 19.7581 ⌀ mm |
| 11 US | 20.5709 ⌀ mm |
| 12 US | 21.3837 ⌀ mm |
| 13 US | 22.1965 ⌀ mm |
⌀ mm to US conversion table
| ⌀ mm | US |
|---|---|
| 14.1 ⌀ mm | 3.03875 US |
| 14.9 ⌀ mm | 4.023 US |
| 15.7 ⌀ mm | 5.00725 US |
| 16.5 ⌀ mm | 5.99149 US |
| 17.3 ⌀ mm | 6.97574 US |
| 18.1 ⌀ mm | 7.95999 US |
| 18.9 ⌀ mm | 8.94423 US |
| 19.8 ⌀ mm | 10.0515 US |
| 20.6 ⌀ mm | 11.0358 US |
| 21.4 ⌀ mm | 12.02 US |
| 22.2 ⌀ mm | 13.0043 US |
Quick answers
Quick answers
- How many ⌀ mm is 1 US?
- 1 US is 12.4429 ⌀ mm.
- How many ⌀ mm is 10 US?
- 10 US is 19.7581 ⌀ mm.
- How many ⌀ mm is 7 US?
- 7 US is 17.3197 ⌀ mm.
The units
About these units
US sizes (US)
American numeric sizes, stepping 2.55 mm of circumference each whole size.
Diameter (mm) (⌀ mm)
The inside distance across the ring. Circumference divided by π.
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