Convert Millimeters of Diameter to US Ring Sizes
1 inner diameter (mm) = -13.078288 us ring sizes. Multiply by 1.2303085, then − 14.308596.
1 mm Ø = -13.07828758 US
Multiply by 1.2303085, then − 14.308596.
Fingers change size with temperature and time of day, and wide bands fit tighter. Have a jeweller confirm before buying. About accuracy
Millimeters of Diameter to US Ring Sizes table
| Millimeters of Diameter | US Ring Sizes |
|---|---|
| 1 mm Ø | -13.078288 US |
| 2 mm Ø | -11.847979 US |
| 3 mm Ø | -10.617671 US |
| 4 mm Ø | -9.3873622 US |
| 5 mm Ø | -8.1570537 US |
| 10 mm Ø | -2.0055114 US |
| 20 mm Ø | 10.297573 US |
| 25 mm Ø | 16.449115 US |
| 50 mm Ø | 47.206827 US |
| 100 mm Ø | 108.72225 US |
| 500 mm Ø | 600.84563 US |
| 1000 mm Ø | 1,215.9999 US |
About these units
The inner diameter (mm) (mm Ø) is a metric unit of ring size, equal to 3.1415927 millimeters of circumference.
The us / canada size (US) is a US customary unit of ring size.
Going the other way, 1 us / canada size = 12.442893 millimeters of diameter. 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 us ring sizes are in a inner diameter (mm)?
- 1 inner diameter (mm) = -13.078288 us ring sizes.
- How do you convert millimeters of diameter to us ring sizes?
- Multiply by 1.2303085, then − 14.308596.
- What is 10 mm Ø in US?
- 10 mm Ø = -2.0055114 US.