Ring Size Calculator — Find Your Size in Seconds

Quick calculator — measure, then convert

Already measured your finger with string or paper? Enter the circumference below, or open the full ring size calculator for diameter and inches too.

Ring size chart online — preview (US 4–10)

Preview: US sizes 4 to 10. See the full ring size chart for sizes 3 to 13.

See the full ring size chart (US 3–13) → or use the ring size converter to switch between systems.

How it works in 3 steps

1. Calibrate once. Match the on-screen outline to a real bank card so one millimetre on screen is one real millimetre.
2. Match your ring. Place a well-fitting ring flat on the screen and adjust the circle to its inside edge — see how to measure ring size for the string method too.
3. Read every system at once. Diameter, circumference, US, UK, EU, Japanese and Indian sizes update live.

Popular guides

Common sizing mistakes in online ring shopping

Most wrong-size returns trace back to the same handful of measuring mistakes — and none of them need special equipment to avoid. Run through this list before you order, especially if the ring cannot be resized.

1. Measuring first thing in the morning

Fingers are at their smallest on a cold morning and swell by up to half a size through the day. A ring sized at 8 a.m. can feel tight every afternoon. Measure in the evening, at room temperature — then repeat on another day and trust the reading that agrees.

2. Using stretchy string or thread

Thread, yarn and elastic string stretch under tension and read small — sometimes by a full size. Use a flat strip of paper about 5 mm wide, a cable tie, or our printable ring sizer, pulled snug but not tight.

3. Measuring the outside of a ring

The band’s thickness is not part of the size. Always measure the inside diameter, from inside edge to inside edge — or match the inside edge with the on-screen sizer above. Outside measurements overshoot by roughly a size.

4. Forgetting the knuckle

The ring has to travel over your knuckle every single day. If your knuckle is visibly wider than the base of your finger, measure both and choose a size between the two — closer to the knuckle measurement if the base is much slimmer, so the ring passes on but does not spin.

5. Measuring the wrong hand — or the wrong finger

Your dominant hand typically measures about half a size larger than the other, and no two fingers match. Measure the exact finger, on the exact hand, that will wear the ring.

6. Trusting an uncalibrated screen or a rescaled printout

An on-screen circle is only as honest as its calibration: one check against a bank card (85.60 mm wide) makes it true to size, and changing browser zoom afterwards silently breaks it. Paper has the same trap — if a printout is not at exactly 100%, the 50 mm check bar on our printable sizer tells you before the circles can lie to you.

Wide band? Size up

A wide band covers more skin and grips the finger over a longer stretch, so it feels noticeably tighter than a slim band of the exact same size. That is why men’s wedding bands — often 6–8 mm wide — catch buyers out, and why stacked rings need the same thinking: two or three slim bands worn together behave like one wide band. A comfort-fit profile (domed on the inside) eases the effect slightly, but if you are between sizes with a wide band, always take the larger one. Find your size with the calculator above, then order half a size up for anything 6 mm or wider.

Full detail in how to measure ring size and our ring size FAQ.

Most-searched sizes

Also in detail: US size 5 · US size 6.5 · US size 7.5 · US size 8.

Frequently asked questions

More answers in the full FAQ.