Digital Calibration & Sizing Engine
Standard:ISO 8653:2016
STEP 1
Calibrate Screen Scale
Hold your debit or credit card vertically flat against the box below. Adjust until the outline matches the short edge (53.98 mm) of your card.
Short Edge (53.98 mm)Physical Card Target204 px
STEP 2Match Your Ring17.30 mm
Place your ring on the circle below. Adjust slider until circle fills the inside diameter.
US 717.3 mm
US 3 (14.1 mm)US 13.5 (22.6 mm)
Direct Dimensions Input
mm
mm
Equivalent units:
5.44 cm|2.14 in
International Sizing Scale
US / Canada7
UK / AustraliaN 1/2
Europe (ISO)54
India / Asia14
Universal Standards
International Ring Size Matrix
ISO 8653
| US / Canada | UK / Australia | Europe (ISO) | India / Asia | Diameter (mm) | Circumference (mm) |
|---|---|---|---|---|---|
| 3 | F | 44 | 4 | 14.1 | 44.2 |
| 3.5 | G | 45 | 5 | 14.5 | 45.5 |
| 4 | H | 47 | 7 | 14.9 | 46.8 |
| 4.5 | I | 48 | 8 | 15.3 | 48.0 |
| 5 | J 1/2 | 49 | 9 | 15.7 | 49.3 |
| 5.5 | K 1/2 | 51 | 10 | 16.1 | 50.6 |
| 6 | L 1/2 | 52 | 11 | 16.5 | 51.9 |
| 6.5 | M 1/2 | 53 | 13 | 16.9 | 53.1 |
| 7 | N 1/2 | 54 | 14 | 17.3 | 54.4 |
| 7.5 | O 1/2 | 56 | 15 | 17.7 | 55.7 |
| 8 | P 1/2 | 57 | 16 | 18.1 | 57.0 |
| 8.5 | Q 1/2 | 58 | 17 | 18.5 | 58.3 |
| 9 | R 1/2 | 59 | 18 | 18.9 | 59.5 |
| 9.5 | S 1/2 | 60 | 19 | 19.3 | 60.8 |
| 10 | T 1/2 | 62 | 20 | 19.8 | 62.1 |
| 10.5 | U 1/2 | 63 | 22 | 20.2 | 63.4 |
| 11 | V 1/2 | 65 | 23 | 20.6 | 64.6 |
| 11.5 | W 1/2 | 66 | 25 | 21.0 | 65.9 |
| 12 | Y | 67 | 26 | 21.4 | 67.2 |
| 12.5 | Z | 68 | 27 | 21.8 | 68.5 |
| 13 | Z+1 | 70 | 28 | 22.2 | 69.7 |
| 13.5 | Z+2 | 71 | 29 | 22.6 | 71.0 |
Documentation & FAQ
Frequently Asked Questions.
What is 7 cm in ring size?
A 7 cm (70 mm) finger circumference equals a US Size 13, UK Size Z+1, European Size 70, and Asian Size 28 to 29.
Is a size 7 ring big for a woman?
No. A US size 7 (17.3 mm inner diameter, 54.4 mm circumference) is the worldwide average ring size for women.
Can I measure my ring size on my phone?
Yes. Use our on-screen tool, place a standard bank card on screen to calibrate the pixel ratio 1:1, and position your ring over the circle.
How many mm is a US size 6 ring?
A US size 6 ring has an inside diameter of 16.5 mm and an inner circumference of 51.9 mm (UK size L 1/2, EU size 52).
What should I do if I am between two ring sizes?
Always size up. Fingers naturally swell in the evening and during warmer temperatures, and wide bands (6mm+) fit tighter than thin bands.