Convert US Ring Sizes to Millimeters of Diameter
1 us / canada size = 12.442893 millimeters of diameter. Multiply by 0.81280429, then + 11.630088.
1 US = 12.44289261 mm Ø
Multiply by 0.81280429, then + 11.630088.
Fingers change size with temperature and time of day, and wide bands fit tighter. Have a jeweller confirm before buying. About accuracy
US Ring Sizes to Millimeters of Diameter table
| US Ring Sizes | Millimeters of Diameter |
|---|---|
| 1 US | 12.442893 mm Ø |
| 2 US | 13.255697 mm Ø |
| 3 US | 14.068501 mm Ø |
| 4 US | 14.881305 mm Ø |
| 5 US | 15.69411 mm Ø |
| 10 US | 19.758131 mm Ø |
| 20 US | 27.886174 mm Ø |
| 25 US | 31.950196 mm Ø |
| 50 US | 52.270303 mm Ø |
| 100 US | 92.910518 mm Ø |
| 500 US | 418.03224 mm Ø |
| 1000 US | 824.43438 mm Ø |
About these units
The us / canada size (US) is a US customary unit of ring size.
The inner diameter (mm) (mm Ø) is a metric unit of ring size, equal to 3.1415927 millimeters of circumference.
Going the other way, 1 inner diameter (mm) = -13.078288 us ring sizes. Ring sizes are all derived from the inner circumference of the band. The US scale adds about 2.55 mm of circumference per size, the ISO standard quotes the circumference in millimetres directly, and France and Spain quote the circumference minus 40. Measure a ring that already fits rather than your finger, at room temperature.
Frequently asked
- How many millimeters of diameter are in a us / canada size?
- 1 us / canada size = 12.442893 millimeters of diameter.
- How do you convert us ring sizes to millimeters of diameter?
- Multiply by 0.81280429, then + 11.630088.
- What is 10 US in mm Ø?
- 10 US = 19.758131 mm Ø.