Ring Size Converter
One measurement, converted to every scale.
- A wide band fits tighter — go up a size for anything deep.
- Fingers swell in heat. Measure at the end of a normal day.
US 7
UK N½ · EU 54.4
17.3 mm across · 54.3 mm around
| US | UK | EU | Diameter | Around |
|---|---|---|---|---|
| 3 | F | 44 | 14.1 mm | 44.2 mm |
| 3½ | G | 45.5 | 14.5 mm | 45.5 mm |
| 4 | H | 46.8 | 14.9 mm | 46.8 mm |
| 4½ | I | 48 | 15.3 mm | 48.0 mm |
| 5 | J½ | 49.3 | 15.7 mm | 49.3 mm |
| 5½ | K½ | 50.6 | 16.1 mm | 50.6 mm |
| 6 | L½ | 51.9 | 16.5 mm | 51.9 mm |
| 6½ | M½ | 53.1 | 16.9 mm | 53.1 mm |
| 7 | N½ | 54.4 | 17.3 mm | 54.4 mm |
| 7½ | O½ | 55.7 | 17.7 mm | 55.7 mm |
| 8 | P½ | 57 | 18.1 mm | 57.0 mm |
| 8½ | Q½ | 58.3 | 18.5 mm | 58.3 mm |
| 9 | R½ | 59.5 | 19.0 mm | 59.5 mm |
| 9½ | S½ | 60.8 | 19.4 mm | 60.8 mm |
| 10 | T½ | 62.1 | 19.8 mm | 62.1 mm |
| 10½ | U½ | 63.4 | 20.2 mm | 63.4 mm |
| 11 | V½ | 64.6 | 20.6 mm | 64.6 mm |
| 11½ | W½ | 65.9 | 21.0 mm | 65.9 mm |
| 12 | Y | 67.2 | 21.4 mm | 67.2 mm |
| 12½ | Z | 68.5 | 21.8 mm | 68.5 mm |
| 13 | Z+1 | 69.7 | 22.2 mm | 69.7 mm |
Sizes are read from inside circumference, the measurement ISO 8653 defines. Have a jeweller confirm before anything is made.
How to find your ring size, and convert it to any scale
Every national ring size scale is derived from one measurement: the inside circumference of the band, in millimeters. US sizes step by about 2.55 mm per whole size, UK sizes run by letter, and European sizes simply state the circumference. Measure once and every scale follows, which is what this converter does.
In the United States, the average woman's ring size is around 6 to 6.5 and the average man's around 9 to 10. Those are starting points for a surprise, not substitutes for a measurement.
Measuring accurately at home
The reliable method is to measure an existing ring that fits the right finger: lay it on a ruler and read the inside diameter across the widest point, in millimeters. Multiply by 3.1416 for the circumference, or just enter the diameter above.
The string-and-paper method works if you are careful. Wrap a thin strip snugly around the base of the finger, mark where it meets, and measure the length — that is the circumference. Do not pull it tight, and do not use anything stretchy.
When to measure, and what changes
Fingers swell. They are largest at the end of the day, in heat, after salt or alcohol, and during pregnancy; they are smallest first thing in the morning and in cold weather. Measure late in the day, at normal room temperature, and take the reading two or three times.
Two adjustments matter. A wide band — anything over about 6 mm — sits tighter, so go up a half size. And the ring has to pass the knuckle: if the knuckle is much larger than the base of the finger, size to the knuckle and accept a slightly loose fit, or have the band sized with beads inside.
Resizing, and when it is not possible
Most plain and pavé-free bands in gold or platinum can be moved a size or two either way by a jeweler. Full eternity bands, channel-set rings, tension settings and anything in titanium, tungsten or ceramic generally cannot be resized at all — those have to be made to size.
| US | UK | EU | Inside diameter | Inside circumference |
|---|---|---|---|---|
| 4 | H | 46.8 | 14.9 mm | 46.8 mm |
| 5 | J½ | 49.3 | 15.7 mm | 49.3 mm |
| 6 | L½ | 51.9 | 16.5 mm | 51.9 mm |
| 7 | N½ | 54.4 | 17.3 mm | 54.4 mm |
| 8 | P½ | 57.0 | 18.1 mm | 57.0 mm |
| 9 | R½ | 59.5 | 19.0 mm | 59.5 mm |
| 10 | T½ | 62.1 | 19.8 mm | 62.1 mm |
| 11 | V½ | 64.6 | 20.6 mm | 64.6 mm |
| 12 | Y | 67.2 | 21.4 mm | 67.2 mm |
| 13 | Z+1 | 69.7 | 22.2 mm | 69.7 mm |
Sizes are derived from inside circumference as ISO 8653 defines them. Half sizes fall midway between the rows above; the converter gives them.
Questions we are asked
- What ring size am I?
- Measure the inside diameter of a ring that fits, in millimeters, and enter it above. A 17.3 mm inside diameter is a US 7; 16.5 mm is a US 6.
- What is the average ring size?
- In the US, around 6 to 6.5 for women and 9 to 10 for men. Height and hand size shift that more than anything else.
- How do I measure ring size without a ring sizer?
- Wrap a strip of paper or a length of non-stretch string around the base of the finger, mark the overlap, and measure the length in millimeters. That length is the inside circumference — enter it above.
- Should I size up for a wide band?
- Yes. Anything wider than about 6 mm wears tighter than a narrow band, so add a half size.
- Can any ring be resized?
- No. Plain precious metal bands usually can, within a size or two. Eternity bands, channel settings, tension settings and rings in titanium, tungsten or ceramic generally cannot.
While You Have It OffRead the ring itself
With the ring in your hand, photograph it: the Ring Identifier reads the setting and the stones together, and gives a range.