Conversions
Ring Size Chart & Conversion Tool
Last updated: May 31, 2026
Written by Blake Boege
A converter and reference chart calculates ring sizes. Users search to convert finger measurements in millimeters to US, UK, or EU ring size standards.
A comprehensive ring size chart converts between US sizes, inside diameter (mm), circumference (mm), and UK/EU sizing standards.
Quick Answer
US ring sizes range from size 3 (diameter 14.1 mm, circumference 44.3 mm) to size 13 (diameter 22.2 mm, circumference 69.7 mm).
Quick reference
US ring sizes range from size 3 (diameter 14.1 mm, circumference 44.3 mm) to size 13 (diameter 22.2 mm, circumference 69.7 mm).
A converter and reference chart calculates ring sizes. Users search to convert finger measurements in millimeters to US, UK, or EU ring size standards.
Ring Size Measurement Helper
Enter either your finger's inside circumference or inside diameter in millimeters to find the corresponding ring sizes:
Calculated best match size is US Size 7. Refer to the table below for full conversions.
US Ring Size
Size 7
17.3 mm Diameter / 54.4 mm Circumference
This measurement is based on standard international conversion charts. Band width and shape can affect actual fit.
Ring Size Sizing Chart (US, UK, & EU)
The table below displays standard ring sizes and their millimeter equivalents. Your matched size is highlighted below:
| US Size | Diameter (mm) | Circumference (mm) | UK Size | EU Size |
|---|---|---|---|---|
| US 3 | 14.1 mm | 44.3 mm | UK F | EU 44 |
| US 3.5 | 14.5 mm | 45.6 mm | UK G | EU 45.5 |
| US 4 | 14.9 mm | 46.8 mm | UK H | EU 46.5 |
| US 4.5 | 15.3 mm | 48 mm | UK I | EU 48 |
| US 5 | 15.7 mm | 49.3 mm | UK J | EU 49 |
| US 5.5 | 16.1 mm | 50.6 mm | UK K | EU 50.5 |
| US 6 | 16.5 mm | 51.8 mm | UK L | EU 51.5 |
| US 6.5 | 16.9 mm | 53.1 mm | UK M | EU 53 |
| US 7 | 17.3 mm | 54.4 mm | UK N | EU 54 |
| US 7.5 | 17.7 mm | 55.7 mm | UK O | EU 55 |
| US 8 | 18.2 mm | 56.9 mm | UK P | EU 56.5 |
| US 8.5 | 18.6 mm | 58.2 mm | UK Q | EU 58 |
| US 9 | 19 mm | 59.5 mm | UK R | EU 59 |
| US 9.5 | 19.4 mm | 60.8 mm | UK S | EU 60.5 |
| US 10 | 19.8 mm | 62.1 mm | UK T | EU 62 |
| US 10.5 | 20.2 mm | 63.4 mm | UK U | EU 63 |
| US 11 | 20.6 mm | 64.6 mm | UK V | EU 64.5 |
| US 11.5 | 21 mm | 65.9 mm | UK W | EU 66 |
| US 12 | 21.4 mm | 67.2 mm | UK X | EU 67 |
| US 12.5 | 21.8 mm | 68.5 mm | UK Y | EU 68.5 |
| US 13 | 22.2 mm | 69.7 mm | UK Z | EU 70 |
Examples
US Size 6 equivalent
Diameter 16.5 mm, Circumference 51.8 mm
US Size 7 equivalent
Diameter 17.3 mm, Circumference 54.4 mm
US Size 8 equivalent
Diameter 18.2 mm, Circumference 56.9 mm
How it works
This reference guide provides an interactive interface and comprehensive lookups to answer questions about ring size chart.
Use the calculators to input values, highlight rows or columns, and solve conversions instantly.
How to measure ring size at home
To measure your finger at home: 1) Wrap a strip of paper or string around the base of the finger you intend to wear the ring on. 2) Mark the spot where the paper overlaps. 3) Measure the length of the paper in millimeters with a standard ruler to get your finger circumference. 4) Check the circumference in our converter above to find your US ring size. It is recommended to measure in the evening when fingers are warmest and at their largest.
US vs UK vs EU ring sizing systems
Different countries use different standards for ring sizing. The US and Canada use a numerical scale based on diameter. The UK, Ireland, and Australia use an alphabetical scale (F to Z). European sizes (EU) correspond directly to the inside circumference of the ring in millimeters (e.g., a ring with a 50mm circumference is size 50). Our chart above converts between all three systems.
Men's vs Women's ring sizing
There is no difference in the sizing standard for men's and women's rings in the US. A US size 7 ring is the exact same size whether it is marketed for men or women. However, women's rings typically range from sizes 3 to 9, while men's rings generally range from sizes 8 to 14 due to differences in average finger thickness.
Is it a US federal holiday?
No, a ring size chart is a conversion tool and reference guide, not a calendar holiday.
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Frequently asked questions
Wrap a strip of paper or string around the base of your finger, mark where it overlaps, and measure the length in millimeters with a ruler. This gives you the circumference, which you can input into our sizer helper to find your US size.
Diameter is the straight distance across the inner opening of a ring. Circumference is the distance all the way around the inner boundary of the ring or your finger.
Yes, the US ring sizing standard (based on diameter and circumference in millimeters) is identical for both men's and women's rings. However, men's rings typically fall in larger sizes (usually 8 to 14) compared to women's rings (usually 3 to 9).
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