Online Ring Sizer
Ring Size Chart
Inside diameter measures across a ring's inner opening; circumference measures around it or your finger. Measurements are in millimetres. Regional equivalents are approximate.
Scroll for more sizes; swipe sideways for more columns. US sizes stay visible. Keyboard: focus the chart and use the arrow keys.
| US / Canada | Inside diameter (mm) | Inside circumference (mm) | UK / Australia | EU / ISO (approx.) | Japan / Asia |
|---|---|---|---|---|---|
| 3 | 14.1 | 44.30 | F | 44 | 4 |
| 3¼ | 14.3 | 44.92 | F½ | 45 | 5 |
| 3½ | 14.5 | 45.55 | G | 46 | Not listed |
| 3¾ | 14.7 | 46.18 | G½ | 46 | 6 |
| 4 | 14.9 | 46.81 | H | 47 | 7 |
| 4¼ | 15.1 | 47.44 | H½ | 47 | Not listed |
| 4½ | 15.3 | 48.07 | I | 48 | 8 |
| 4¾ | 15.5 | 48.69 | I½ | 49 | Not listed |
| 5 | 15.7 | 49.32 | J | 49 | 9 |
| 5¼ | 15.9 | 49.95 | J½ | 50 | Not listed |
| 5½ | 16.1 | 50.58 | K | 51 | 10 |
| 5¾ | 16.3 | 51.21 | K½ | 51 | Not listed |
| 6 | 16.5 | 51.84 | L | 52 | 11 |
| 6¼ | 16.7 | 52.46 | L½ | 52 | 12 |
| 6½ | 16.9 | 53.09 | M | 53 | 13 |
| 6¾ | 17.1 | 53.72 | M½ | 54 | Not listed |
| 7 | 17.3 | 54.35 | N | 54 | 14 |
| 7¼ | 17.5 | 54.98 | N½ | 55 | Not listed |
| 7½ | 17.7 | 55.61 | O | 56 | 15 |
| 7¾ | 17.9 | 56.23 | O½ | 56 | Not listed |
| 8 | 18.1 | 56.86 | P | 57 | 16 |
| 8¼ | 18.3 | 57.49 | P½ | 57 | Not listed |
| 8½ | 18.5 | 58.12 | Q | 58 | 17 |
| 8¾ | 18.8 | 59.06 | Q½ | 59 | Not listed |
| 9 | 19.0 | 59.69 | R | 60 | 18 |
| 9¼ | 19.2 | 60.32 | R½ | 60 | Not listed |
| 9½ | 19.4 | 60.95 | S | 61 | 19 |
| 9¾ | 19.6 | 61.58 | S½ | 62 | Not listed |
| 10 | 19.8 | 62.20 | T | 62 | 20 |
| 10¼ | 20.0 | 62.83 | T½ | 63 | 21 |
| 10½ | 20.2 | 63.46 | U | 63 | 22 |
| 10¾ | 20.4 | 64.09 | U½ | 64 | Not listed |
| 11 | 20.6 | 64.72 | V | 65 | 23 |
| 11¼ | 20.8 | 65.35 | V½ | 65 | Not listed |
| 11½ | 21.0 | 65.97 | W | 66 | 24 |
| 11¾ | 21.2 | 66.60 | W½ | 67 | Not listed |
| 12 | 21.4 | 67.23 | X | 67 | 25 |
| 12¼ | 21.6 | 67.86 | X½ | 68 | Not listed |
| 12½ | 21.8 | 68.49 | Y | 68 | 26 |
| 12¾ | 22.0 | 69.12 | Z | 69 | Not listed |
| 13 | 22.2 | 69.74 | Z½ | 70 | 27 |
| 13¼ | 22.4 | 70.37 | Not listed | 70 | Not listed |
| 13½ | 22.6 | 71.00 | Z1 | 71 | Not listed |
Reading the Chart & International Standards
Jewelers around the world use different sizing scales based on either inside diameter or inside circumference:
US & Canada (Numerical)
Ranges from size 3 to 13.5 in quarter increments. Each full size increase represents approximately 0.8 mm increase in inside diameter (or 2.5 mm in circumference).
UK & Australia (Alphabetical)
Uses letters from F to Z in half-letter increments (e.g., L, L½, M). Governed by the British standard BS 6820 where each letter step equals 1.25 mm of circumference.
EU & ISO 8653 (Metric)
The official international standard specifies ring size directly by inner circumference in millimeters. For example, an EU size 52 corresponds to a 52.0 mm inside circumference.
Japan & East Asia (Numerical)
Common across Japan, China, and Southeast Asia. Uses numbers 1 to 27 based on inner diameter, with size 1 beginning at 13.0 mm.
Retailer charts can vary. “Not listed” means the source has no equivalent label. Quarter US sizes and half UK letters are included where listed. EU / ISO is circumference rounded to the nearest millimetre, so the same EU label can appear on more than one row.
Diameter follows the GIA reference chart. Circumference is calculated as π × diameter and displayed to two decimal places; this display precision does not imply measurement accuracy.
Source: GIA International Ring Size Chart · gia-v1 · last verified . View sources and conversion rules.
Calculate from a measurement · Convert a known size · Download printable PDF sizer
Frequently Asked Questions
What is the average ring size for women and men?
The most common ring sizes for women are US 6 to 7 (UK L to N, EU 52 to 54). For men, the average ring size is US 9 to 10 (UK R to T, EU 60 to 62). However, every finger is unique and measuring beforehand is always recommended.
How do US, UK, and European ring sizes compare?
The United States and Canada use numerical sizes from 3 to 13.5 based on inside diameter. The United Kingdom, Australia, and South Africa use alphabetical letters from A to Z based on inside circumference. The European Union and ISO 8653 standard represent ring sizes directly by inner circumference in millimeters (e.g., EU 54 = 54.0 mm circumference).
Which measurement is the most reliable when ordering jewelry online?
Inside diameter in millimeters (mm) is the universal engineering standard. Millimeter measurements do not change across regions, whereas letter or numerical labels can have slight variance between jewelers.