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Convert US ring sizes to diameter in millimeters with circumference measurements
Diameter (mm) ≈ 11.63 + (US Size × 0.4)
Circumference (mm) = Diameter × π
| US Size | UK Size | Diameter (mm) | Circumference (mm) |
|---|---|---|---|
| 3 | F | 14.1 mm | 44.2 mm |
| 3.5 | G | 14.5 mm | 45.5 mm |
| 4 | H | 14.9 mm | 46.8 mm |
| 4.5 | I | 15.3 mm | 48.0 mm |
| 5 | J | 15.7 mm | 49.3 mm |
| 5.5 | K | 16.1 mm | 50.6 mm |
| 6 | L | 16.5 mm | 51.9 mm |
| 6.5 | M | 16.9 mm | 53.1 mm |
| 7 | N | 17.3 mm | 54.4 mm |
| 7.5 | O | 17.7 mm | 55.7 mm |
| 8 | P | 18.2 mm | 57.2 mm |
| 8.5 | Q | 18.6 mm | 58.4 mm |
| 9 | R | 19.0 mm | 59.7 mm |
| 9.5 | S | 19.4 mm | 60.9 mm |
| 10 | T | 19.8 mm | 62.2 mm |
| 10.5 | U | 20.2 mm | 63.5 mm |
| 11 | V | 20.6 mm | 64.8 mm |
| 11.5 | W | 21.0 mm | 66.0 mm |
| 12 | X | 21.4 mm | 67.2 mm |
| 12.5 | Y | 21.8 mm | 68.5 mm |
| 13 | Z | 22.2 mm | 69.8 mm |
US ring sizing is a numerical system used primarily in the United States to measure ring sizes. The system uses whole and half sizes, typically ranging from size 3 to 13 for adults. Each size increase represents an increase of approximately 0.4mm in the inner diameter of the ring.
The US ring size system is based on the inner circumference of the ring measured in inches, then converted to a numerical size. The most common sizes for women range from 5 to 7, while men's sizes typically range from 8 to 10.5.
Unlike some international sizing systems that use letters or different numerical scales, the US system provides a straightforward numerical progression that makes it easy to go up or down in size increments.
Method 1: Using an Existing Ring
Method 2: Using String or Paper
Important Tips: Measure your finger at the end of the day when it's warmest (fingers are slightly larger). Consider the width of the band - wider bands require slightly larger sizes. Measure multiple times for accuracy.
The most common ring size for women in the US is size 6 to 7, which corresponds to a diameter of 16.5mm to 17.3mm. However, ring sizes can vary significantly based on individual finger size and which finger the ring is worn on.
The most common ring size for men is typically between size 9 and 10, corresponding to a diameter of 19.0mm to 19.8mm. Men's rings are generally larger and often wider bands, which may require going up a half size for comfort.
Ring sizes can vary by 0.5 to 1 full size between different fingers on the same hand. The dominant hand's fingers are often slightly larger. Ring fingers tend to be slightly larger than index fingers, and middle fingers are typically the largest.
Yes, ring size can change due to weight gain or loss, temperature, humidity, pregnancy, aging, and water retention. Fingers are typically slightly larger in warm weather and at the end of the day. It's normal for ring size to fluctuate by up to half a size throughout the day.
US ring sizes use a numerical system (3-13), while UK ring sizes use letters (A-Z). The sizes don't directly correspond - for example, US size 6 equals UK size L. However, both systems are based on the same physical measurements (diameter and circumference in millimeters).
Yes, wider bands (8mm or more) typically require sizing up by 0.25 to 0.5 sizes for the same comfort level. Wide bands cover more surface area of the finger and can feel tighter than thin bands of the same inner diameter. Always try on similar width bands when determining your size.