Find your ring size
Four ways to get there: convert a size you already know, measure a ring that fits, measure your finger with a piece of string, or lay a ring on the screen and match it against true-to-life circles. Everything converts between US, UK, Europe, India and Japan.
Take a ring that fits the right finger and measure straight across the inside of the band, edge to edge, in millimetres. A ruler works; callipers are better.
Millimetres. Most adult rings fall between 15 and 21 mm.
Wrap a strip of paper or a piece of non-stretchy string around the base of the finger, mark where it overlaps, then lay it flat against a ruler. Snug, not tight — it has to pass over your knuckle.
Millimetres. Most adult fingers fall between 47 and 66 mm.
First, calibrate your screen
Every screen is a different size, so the circles below can only be true-to-life once we know yours. Hold any bank card flat against the rectangle and drag the slider until they match exactly — every credit and debit card in the world is the same 85.60 × 53.98 mm, which makes it a free and perfectly accurate ruler.
Rest a ring inside a dashed circle, then read the two colours:
Full ring size chart
Inside diameter is the measurement across the middle of the band. Circumference is the distance around the inside — and is also, by definition, the European ISO size.
| US / Canada | UK / Australia | Europe (ISO) | India / Japan / China | Diameter | Circumference |
|---|
Getting it right the first time
Measure at the end of the day
Fingers swell as the day goes on and in warm weather. A ring sized first thing on a cold morning will feel tight by evening. Measure warm and late.
Check the knuckle
The ring has to pass over your knuckle and then sit without spinning. If your knuckle is much wider than the base of the finger, size to the knuckle and have the band fitted with sizing beads.
Wide bands run tight
A band over about 6 mm wide touches more of your finger and feels snugger at the same measurement. Go up a quarter to a half size.
Buying a surprise?
Borrow a ring she already wears on that finger and measure the inside diameter. Failing that, US 6 to 6½ is the most common women's size and US 9 to 10 the most common men's. Size up rather than down — a ring can be made smaller far more easily than larger.
Know the size. Now check the stone.
See what a diamond actually costs at retail — and the far smaller number it resells for.
Value a diamondEvery size, converted
A page for each size with the full chart, how to check it, and what to do if you are between sizes.