Ring Size Guide

UK ring size chart

Every whole UK size, with the inside circumference and the inside diameter. Circumference is the figure a jeweller works from. Diameter is what you get if you measure across the inside of a ring you already own.

Half sizes exist for every letter and we make to them as standard. The figures follow the British Standard, where size A is 37.83mm inside circumference.

The US column is a cross-reference, not a conversion to order from. Published UK–US charts genuinely disagree with each other by up to a quarter of a US size, and they disagree most at the small end of the scale. If you are having a ring made here, give us the UK letter or the millimetres and let us work from that.

Ring sizes UK in mm: convert a measurement

The chart above goes letter first. This one goes the other way, for when you already have a number — because you measured a ring that fits, or a sizer gave you a figure in millimetres, or a European jeweller quoted you one. Find your measurement, read off the letter.

Check which measurement you have before you look it up, because the two are easy to confuse and the answer is very different. The circumference is the distance all the way around the inside of the band — what you get from a paper strip around a finger, and the figure European sizes quote directly, so a “size 58” is 58mm around. The diameter is the distance straight across the inside of a ring, which is what a ruler gives you when you lay a ring flat. Circumference is roughly three and a bit times the diameter.

Circumference in mm to UK ring size

Diameter in mm to UK ring size

In half-millimetre steps, because diameter compresses the scale: one whole millimetre across is more than three UK sizes, so rounding to the nearest millimetre here is how people end up two sizes out.

Both tables give the nearest UK size rather than a range, and both include half sizes. A measurement of a finger is already an approximation — fingers change size through the day and through the year — so a letter and a half-letter either side is the honest width of the answer. If you land almost exactly between two, take the larger: a ring that is marginally loose can be worn, and a ring that will not pass the knuckle cannot.

How to measure ring size

There are three methods that give a size you can order from. Everything else is a guess.

1. Have your finger measured

A jeweller measures with a calibrated set of steel rings, so you feel the actual fit rather than reading a number off a scale. It takes a minute and it is the most accurate method there is. We do this free of charge at our Hatton Garden showroom.

2. Use a ring sizer

A plastic or metal ring sizer works like a belt: you slide it on, adjust it until it passes over the knuckle with slight resistance, and read the letter. Check it more than once, on different days, because fingers change through the day.

3. Measure a ring they already wear

Measure the inside diameter across the widest point, then find it in the chart above. It has to be a ring worn on the same finger of the same hand, because the two hands are rarely the same size.

How not to measure ring size

The string trick is everywhere online and it does not work. String stretches and a ring does not. Paper strips crease, and tape measures are not marked finely enough. A whole UK size is 1.25mm of circumference, so being 2mm out puts you nearly two sizes wrong, which is the difference between a ring that fits and one that will not go on.

Fingers also swell. They are largest at the end of the day, in warm weather and after exercise, and smallest first thing on a cold morning. Measure at a normal time of day, at a normal temperature, and measure more than once.

How to find a ring size in secret

If the ring is a surprise, you cannot simply ask. Four things that work:

1. Borrow a ring they wear. Take one they wear on the correct finger and bring it to us. We will measure it against a calibrated set and give it straight back.
2. Ask someone close to them. A sister, a best friend or a mother often knows, and can usually find out without raising suspicion.
3. Try rings on together. Browsing a jeweller and trying things on for fun is normal. Note the size before you leave.
4. Order slightly large. A ring that is a little big can be worn on the day and sized down afterwards. A ring that is too small cannot be worn at all, and that is the moment you are trying to protect.

Whichever you use, write the size down as soon as you have it. It is exactly the sort of thing you are certain you will remember and then do not.

Average ring size in the UK

The average women’s ring size in the UK is around L, with most falling between G and T. The average men’s size is around T.

Use these to sense check a size, not to choose one. Averages are a wide range and hand size does not track height or build closely enough to guess from.

What happens if the size is wrong

If the ring is too big

It spins, and any stone swivels to one side under its own weight so the diamond ends up facing your palm. Pushed back into place several times a day, the band slowly goes oval. The real risk is losing it, because a ring that turns freely will come off over a cold knuckle without you noticing.

If the ring is too small

Never force it on. A ring that has to be forced can be very difficult to remove, and a finger swelling behind a tight band is a genuine medical problem rather than an inconvenience. A band worn too tight also carries daily pressure it was not designed for, and can eventually crack at the shank.

Can a ring be resized?

Usually yes. A jeweller cuts the shank and either removes metal to make it smaller or adds a matching piece to make it larger, then solders, files and polishes until the join cannot be seen. One or two sizes in either direction is routine work.

Going further than that starts to change the ring. Sizing up a long way thins the band at the bottom, and sizing down a long way can throw the proportions of a setting out.

Rings that cannot be resized

• Full eternity rings. Diamonds run the whole way round, so there is no plain shank to cut. Changing the size means remaking the ring.
• Tension settings. The stone is held by the spring of the metal, so altering the band alters the grip that holds the diamond in place.
• Milgrain and heavy engraving. The pattern runs continuously around the band and will not line up across a join.
• Some inlays and ceramics. Zirconium, tungsten and ceramic bands cannot be cut and soldered at all.

This is why the size matters most on exactly the rings that are hardest to change. If you are set on a full eternity band, measure properly first.

Ring size questions, answered

Getting it right

Measure with a proper tool, measure more than once, and write the answer down. If the ring is a surprise and you are not certain, tell us. We would rather size a ring afterwards than have it not fit on the day.