How to find your ring size at home
You don’t need a jeweler’s sizing tool to get close to your ring size. There are two ways to do it at home, and one is a lot more reliable than the other.
Method 1: measure a ring that already fits (best)
If you have a ring that fits the finger you’re buying for, measure across the inside of it.
- Lay the ring flat on a table, or hold it against the screen with the ruler set to mm.
- Measure the inside diameter — from inner edge to inner edge, through the middle. Don’t include the metal.
- Measure across a couple of different directions and use the largest number. Rings are rarely perfectly round.
- Look up the diameter in the chart below.
Half a millimeter of diameter is roughly one half size, so take your time over this.
Method 2: measure your finger
- Wrap a thin strip of paper or a piece of string around the base of your finger.
- Mark where it overlaps, then lay it flat and measure from the end to the mark. That length is your finger’s circumference.
- Find the circumference in the chart.
This method is less accurate. String stretches, paper creases, and your finger changes size during the day — it’s usually biggest in the evening and when it’s warm. Measure two or three times and lean towards the larger result. If your knuckle is much wider than the base of your finger, measure the knuckle as well: the ring has to fit over it.
Ring size chart
US sizes go up by about 0.81 mm of diameter per whole size. The EU size is simply the inside circumference in millimeters.
| US | UK (approx.) | EU | Inside diameter | Circumference |
|---|---|---|---|---|
| 4 | H | 47 | 14.9 mm | 46.8 mm |
| 5 | J½ | 49 | 15.7 mm | 49.3 mm |
| 6 | L½ | 52 | 16.5 mm | 51.9 mm |
| 7 | N½ | 54 | 17.3 mm | 54.4 mm |
| 8 | P½ | 57 | 18.1 mm | 57.0 mm |
| 9 | R½ | 60 | 18.9 mm | 59.5 mm |
| 10 | T½ | 62 | 19.8 mm | 62.1 mm |
| 11 | V½ | 65 | 20.6 mm | 64.6 mm |
| 12 | Y | 67 | 21.4 mm | 67.2 mm |
If you fall between two sizes, choose the larger one. A ring that is slightly loose can be adjusted easily; one that won’t go over your knuckle can’t be worn at all.
A few things worth knowing
- Wide bands fit tighter. For a band wider than about 6 mm, go up half a size.
- Charts differ between makers, especially for UK letter sizes. If the shop publishes its own chart, use that one.
- Screens need calibrating for this to work. A ruler on an uncalibrated screen can easily be 10% off, which is more than one ring size. Use the Calibrate button and a bank card first — it takes a minute. Why this matters.
If the ring is a gift or an expensive one, it’s still worth having a jeweler confirm the size before it’s engraved or resized.