What is my ring size?
Enter a measurement or a size you already know — the converter gives your size in every system, plus the diameter in millimetres.
Input: 17.3 mm
Your size is US 7 (UK N½, EU 54).
Measurement check Exact table match
Measurement check Inner diameter from a ring that already fits is usually the strongest home input. Re-measure across the widest inner points and check wide-band fit if needed.
- US
- 7
- UK
- N½
- EU / ISO
- 54
- Japan
- 14
- CH / IT / ES
- 14
- Inner diameter, millimetres
- 17.32
- Circ mm
- 54.4
Why this size?
Your input maps to US 7 — UK N½, EU 54, JP 14, Ø 17.32 mm.
Calculated dimensions are rounded chart values, not a measured accuracy guarantee. Ruler placement, print scale, screen calibration and the finger can change the result. Confirm with a physical sizer before ordering.
More options
Choose the fit problem and get the safest next step before resizing, replacing or buying another ring.
Wide band or comfort-fit Too loose or spinning Non-resizable or brand ring Smart-ring fit issue
| US | UK | EU | JP | CH | Inner diameter, millimetres | Circ mm |
|---|---|---|---|---|---|---|
| 3 | F½ | 44 | 4 | 4 | 14.07 | 44.2 |
| 3.5 | G½ | 45 | 5 | 5 | 14.48 | 45.5 |
| 4 | H½ | 47 | 7 | 7 | 14.88 | 46.8 |
| 4.5 | I½ | 48 | 8 | 8 | 15.29 | 48.0 |
| 5 | J½ | 49 | 9 | 9 | 15.70 | 49.3 |
| 5.5 | K½ | 51 | 10 | 11 | 16.10 | 50.6 |
| 6 | L½ | 52 | 12 | 12 | 16.51 | 51.9 |
| 6.5 | M½ | 53 | 13 | 13 | 16.92 | 53.1 |
| 7 | N½ | 54 | 14 | 14 | 17.32 | 54.4 |
| 7.5 | O½ | 56 | 15 | 16 | 17.73 | 55.7 |
| 8 | P½ | 57 | 16 | 17 | 18.14 | 57.0 |
| 8.5 | Q½ | 58 | 17 | 18 | 18.54 | 58.3 |
| 9 | R½ | 60 | 18 | 20 | 18.95 | 59.5 |
| 9.5 | S½ | 61 | 19 | 21 | 19.35 | 60.8 |
| 10 | T½ | 62 | 20 | 22 | 19.76 | 62.1 |
| 10.5 | U½ | 63 | 22 | 23 | 20.17 | 63.4 |
| 11 | V½ | 65 | 23 | 25 | 20.57 | 64.6 |
| 11.5 | W½ | 66 | 24 | 26 | 20.98 | 65.9 |
| 12 | Y | 67 | 25 | 27 | 21.39 | 67.2 |
| 12.5 | Z | 68 | 26 | 28 | 21.79 | 68.5 |
| 13 | Z½ | 70 | 27 | 30 | 22.20 | 69.7 |
Three ways to find it
- From a ring you own: measure the inner diameter in mm and enter it above (most accurate).
- From your finger: wrap a paper strip around the base, measure the overlap in mm, and use “Circumference (mm)”.
- On screen: use the on-screen ring sizer to match a ring you own.
Full detail in how to measure your ring size, or browse the chart.
Frequently asked questions
What is my ring size?
Measure the inner diameter of a ring that fits, in millimetres, and enter it above — or wrap a paper strip around your finger and enter the circumference. The converter gives your US, UK, EU and Japanese size instantly.
How do I find my ring size in mm?
A ring’s inner diameter in millimetres maps directly to a size: 16.5 mm ≈ US 6, 17.3 mm ≈ US 7, 18.9 mm ≈ US 9. Use the “Diameter (mm)” option above.
What is the average ring size?
About US 6–6½ for women and US 9–10 for men. See the average ring size page for full ranges.