Ordering a ring online is exciting, until the checkout asks for a size and you have no idea what yours is. Guess wrong and the ring spins around your finger, or worse, will not pass your knuckle. This free little calculator takes one simple measurement and turns it into your ring size in US, UK, European and Japanese sizing, and it adjusts the result for how snug you like your rings and how wide the band is.
How the Ring Size Calculator works
Wrap a thin strip of paper or a piece of string around the base of the finger you want to size, mark where it overlaps, then measure that length with a ruler. Enter it above, choose how you like your rings to fit and how wide the band is, and your size appears instantly in four sizing systems. No measurement at hand? Enter the inside diameter of a ring that already fits. Wide bands and large knuckles both call for a little extra room, so the calculator adds it for you. Use Try an example to see how it works, Save my size to keep your result on this device, and Copy my size to paste it into a shopping note or send it to a friend.
Quick sizing tips
- Measure at the end of the day. Fingers are smallest in the morning and when cold, and largest in the evening or in warm weather.
- Measure more than once. Take two or three readings on different days and use the average.
- Mind the knuckle. The ring has to slide over it, so if your knuckle is larger, choose the size that passes the knuckle and add a ring guard if it spins.
- Wide bands fit tighter. A band over 6 mm usually needs a half size up from a thin band.
- Each finger is different. Your dominant hand is often a little larger, so measure the exact finger you plan to wear the ring on.
- Between sizes? Go up if you have a wide band or a large knuckle, and down if you like a close fit with a thin band.
