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How to measure your ring size at home without a ring sizer

A ring that's too tight stays in its box; a ring that's too loose ends up at the bottom of a bag. The good news: you can measure your ring size at home in two minutes, with a piece of string or a ring you already wear. Here's how to do it, and how to read the French and US sizes you'll come across online.

What a ring size means

In France, a ring size corresponds to the circumference of the finger in millimetres. A size 54 ring has an inner circumference of about 54 mm. It's easy to remember: if your finger measures 57 mm round, you're a size 57.

American (US) sizes follow a different scale, numbered from about 1 to 13. That's why our product pages show both: “54 (US 7)” means French size 54, which is US size 7.

Method 1: measure a ring you already wear

This is the most reliable method, if you have a ring that fits the intended finger well.

  • Lay the ring flat on a ruler marked in millimetres.
  • Measure the inner diameter, from one inside edge to the other, without counting the thickness of the metal.
  • Multiply this diameter by 3.14: you get the circumference, and therefore the French size. A diameter of 17.2 mm gives 17.2 × 3.14 = 54.

The chart below gives the match between diameter and size directly, with no maths needed.

Method 2: measure your finger with string or a strip of paper

  • Cut a thin strip of paper or a piece of string that doesn't stretch.
  • Wrap it around the base of your finger, without pulling it tight: it should be able to turn.
  • Mark the point where it meets with a pen.
  • Unwind it and measure the length up to the mark, in millimetres: that's your French size.

Then check that the ring will go over your knuckle: if your knuckle is wider than the base of your finger, measure around the knuckle too and go for a size between the two.

Ring size conversion chart

French size (circumference in mm) Inner diameter US size
52 16.6 mm 6
54 17.2 mm 7
57 18.1 mm 8
59 18.8 mm 9
62 19.7 mm 10
64 20.4 mm 11
67 21.3 mm 12
69 22 mm 13

Conversions between French and US sizes are rounded to the nearest millimetre: from one manufacturer to another, the same US size can vary slightly.

Pitfalls that skew the measurement

  • Time of day and temperature. Fingers swell a little in the heat and at the end of the day, and shrink in the cold. Measure at a normal temperature, ideally in the late afternoon.
  • Which hand. The fingers of the hand you use most are often slightly wider. Measure the exact finger, on the exact hand, where you'll wear the ring.
  • Band width. A wide ring, such as a signet ring or a thick band, feels tighter than a thin band of the same size. For a band more than 6 mm wide, go one size up.
  • Between two sizes? Choose the larger one. A slightly loose ring can still be worn; a ring that's too small won't go over the knuckle.
  • Printable ring sizers found online are only accurate if your printer prints at 100% scale. Check with a ruler before relying on one.

Buying a ring without knowing the size

For a surprise, discreetly borrow a ring the person wears on the same finger, and measure its inner diameter as in method 1. Failing that, the most common sizes are around 52 to 54 for a woman and 59 to 62 for a man, but these are only averages.

The safest option is an adjustable ring, whose open band adapts to several sizes. You'll find them in our Rings department.

The right material for a ring worn every day

A ring is worn all the time: it rubs, and comes into contact with water and soap. Stainless steel and titanium steel don't tarnish or rust, which makes them good choices for an everyday ring. To find out more, read our stainless steel jewellery guide.

Find your ring

On each product page, the available sizes are shown as French sizes with their US equivalent: just choose the one you've just measured.