Ring Size FAQs
The questions jewellers get asked most, answered in plain language. Each answer links to a fuller guide if you want the detail.
Quick answer
Most sizing problems come down to three things: measure at the right time of day, measure the inside of the ring, and size up rather than down when you are unsure.
Is it better to size up or down?
Size up. A ring that is slightly loose can be tightened with sizing beads or resized down cheaply. A ring that will not pass your knuckle is unwearable, and stretching a band up is harder and more expensive.
Can ring sizes change over time?
Yes. Weight change, pregnancy, medication, salt, heat and age all change finger size. Most people move up around half a size between their twenties and their fifties. Remeasure every few years.
How much does resizing cost?
A simple gold band resized by one or two sizes is usually inexpensive. Platinum, patterned bands, and rings with stones set all the way round cost much more, and some cannot be resized at all. Ask before you buy.
Frequently asked questions
How do I measure my ring size?
Wrap string around the base of your finger, mark where it meets, measure that length in millimetres, and divide by 3.14 to get the inside diameter. Enter the result in the converter.
What if I am between sizes?
Choose the larger size. Rings can be sized down more easily than up, and fingers swell during the day and in warm weather.
Are UK and US ring sizes different?
Yes. The UK uses letters and the US uses numbers. A UK N½ is roughly a US 7.
How do I secretly measure someone's ring size?
Borrow a ring they already wear on the correct finger and measure the inside diameter, or press it into soap to take an impression.
Does temperature affect ring size?
Yes. Fingers can change by up to half a size between a cold morning and a hot afternoon, so measure at room temperature.
How much bigger is one ring size in mm?
About 0.8 mm of inside diameter, or roughly 2.5 mm of inside circumference, per full US size.
Do wide bands need a bigger size?
Usually. Bands wider than about 6 mm cover more of your finger and feel tighter, so go up a quarter to a half size.
Keep reading
For an expensive ring, confirm the size with a jeweller before ordering — see the ring size FAQs for resizing advice.