Guide

Ring Size Guide

A ring that does not fit cannot be worn, and if it is a proposal or a gift that matters. This guide covers how to measure ring size properly, the full UK chart, how to find a size without giving the surprise away, and what can be done if the size turns out to be wrong.

What is ring size?

Ring size is the inside measurement of the band. In the UK it is written as a letter, from A to Z, and each whole letter adds 1.25mm to the inside circumference. Half sizes sit between the letters, so the real steps are around 0.62mm.

Most of the world measures the same thing differently. The UK and Ireland use letters, the United States uses numbers, and much of Europe uses the circumference in millimetres directly. They all describe the same band, so any of them can be converted.

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.

UK sizeCircumferenceDiameter
A37.83mm12.04mm
B39.08mm12.44mm
C40.32mm12.84mm
D41.57mm13.23mm
E42.82mm13.63mm
F44.06mm14.03mm
G45.31mm14.42mm
H46.56mm14.82mm
I47.80mm15.22mm
J49.05mm15.61mm
K50.30mm16.01mm
L51.54mm16.41mm
M52.79mm16.80mm
N54.04mm17.20mm
O55.28mm17.60mm
P56.53mm17.99mm
Q57.78mm18.39mm
R59.02mm18.79mm
S60.27mm19.18mm
T61.52mm19.58mm
U62.76mm19.98mm
V64.01mm20.38mm
W65.26mm20.77mm
X66.50mm21.17mm
Y67.75mm21.57mm
Z69.00mm21.96mm
Z+170.24mm22.36mm
Z+271.49mm22.76mm
Z+372.74mm23.15mm
Z+473.98mm23.55mm
Z+575.23mm23.95mm
Z+676.48mm24.34mm

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.

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

How do I measure my ring size?

The three reliable methods are a ring sizer tool, a jeweller measuring your finger with a calibrated set of steel rings, and measuring an existing ring that already fits the correct finger. String, paper strips and tape measures are not accurate enough for a ring.

What is the average ring size in the UK?

In the UK the average women's ring size is around L, with most falling between G and T. The average men's ring size is around T. These are starting points for a guess, not a substitute for measuring.

How much does one UK ring size change the fit?

One whole letter is 1.25mm of inside circumference, which is roughly 0.4mm of diameter. That is small enough that half sizes exist and matter, and it is why a string cannot give you a usable answer.

Can a ring be resized?

Most plain and partly set rings can be resized by a jeweller, usually by one or two sizes in either direction. Full eternity rings cannot, because the diamonds run the whole way round and the spacing cannot be altered. Heavily engraved bands, milgrain work and tension settings are also difficult or impossible to resize without visible marks.

What happens if a ring is too big?

It spins on the finger, and any stone will swivel to one side under its own weight. Over time the band takes on an oval shape from being pushed back into place, and there is a real risk of losing it.

How can I find someone's ring size without them knowing?

Borrow a ring they already wear on the right finger and have it measured, ask a close friend or family member, try rings on together while browsing, or bring a ring in to be measured against a calibrated set.

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.