The quickest accurate way to find your ring size at home is to measure the inside circumference of your finger in millimeters and look it up in a ring size chart. A US size 7, the most common women’s size, is about 54.4 mm around. A men’s size 10 is about 62.0 mm.
Here are three ways to get that number, from most to least reliable.
Method 1: Use a ring that already fits
If you have a ring that fits the finger you’re buying for, it’s the best guide you have.
- Print the actual-size ring sizer at 100% (“Actual size” in the print dialog). Check the 100 mm bar with a ruler first.
- Lay the ring on the circles. Your size is the circle whose line sits just inside the ring’s inner edge.
- If it falls between two circles, choose the larger one.
No printer? Measure straight across the inside of the ring with a ruler, edge to edge, in millimeters. That’s the inside diameter. 17.3 mm is a US 7, 18.1 mm a US 8 and 18.9 mm a US 9.
Method 2: Paper strip around your finger
- Cut a strip of paper about 1/4 inch (6 mm) wide and 4 inches long. Paper is better than string, which stretches and twists.
- Wrap it snugly around the base of your finger. It should slide over the knuckle with a little resistance.
- Mark where the end overlaps, unwrap it, and measure from the end to the mark in millimeters.
- Find that circumference in the chart. Or use the formula: US size = (circumference in mm − 36.5) ÷ 2.55.
Example: a strip that measures 56.9 mm gives (56.9 − 36.5) ÷ 2.55 = 8, so a US size 8.
Method 3: The printable finger strip
The ring size chart also has a cut-out finger strip with US sizes printed on it. Wrap it around your finger and read the size where the 0 line meets the scale.
Common sizes at a glance
| US size | Inside diameter | Circumference |
|---|---|---|
| 5 | 15.7 mm | 49.3 mm |
| 6 | 16.5 mm | 51.8 mm |
| 7 | 17.3 mm | 54.4 mm |
| 8 | 18.1 mm | 56.9 mm |
| 9 | 18.9 mm | 59.5 mm |
| 10 | 19.7 mm | 62.0 mm |
| 11 | 20.5 mm | 64.6 mm |
| 12 | 21.4 mm | 67.1 mm |
The full chart adds half sizes plus UK, EU and Japanese sizes. For men’s sizes 8 to 15 there’s a separate men’s ring size chart.
Tips for a size that actually fits
- Measure at the end of the day. Fingers are smaller in the morning and when cold, and swell in heat and after exercise.
- Measure three or four times and use the number that comes up most often.
- Large knuckles: measure both the base of the finger and the knuckle, and pick a size in between so the ring can get over the knuckle.
- Wide bands (about 6 mm or wider) feel tighter. Many jewelers suggest going up half a size.
- Your dominant hand is often slightly larger. Measure the exact finger the ring is for.
- Between two sizes? Choose the larger one. A ring that’s slightly loose is easier to resize than one that won’t go on.
Converting between countries
US and Canada use numbers (3 to 15), the UK and Australia use letters (F to Z+), and most of Europe uses the inside circumference in millimeters, so an EU 54 is about a US 7. Japan uses its own numbers. All four systems are side by side in the ring size chart.