calcs.homes
calcs.homes
Measure your finger with a string or strip of paper, then enter the circumference (or diameter, if you measured a ring you already own) to find your size. Ring measurements are in millimeters worldwide, so there's no US/EU toggle needed here.
Estimate only — get sized in person at a jeweler for an exact fit, especially for wide bands.
Wrap a strip of paper or string snugly around the base of your finger, mark where it overlaps, then measure that length in millimeters — that's your circumference. If you already have a ring that fits, measure straight across the inside edge for the diameter instead, and we multiply by pi to get circumference. We then match that number against a standard sizing table (US half-sizes 4 to 12, each paired with its circumference and diameter), interpolating between rows for values that fall in between, and separately convert to EU/ISO size by subtracting 40 from the circumference in millimeters.
Circumference is the dimension that actually determines whether a ring fits, which is why sizing charts are built around it rather than diameter — diameter is included only because it's easier to measure off a ring you already own by laying it flat. The EU/ISO conversion (circumference minus 40) is the standard formula European jewelers use, which is why US and EU numbers never line up and always need converting rather than being read as the same scale.
Fingers swell slightly with heat and activity — measure at the end of the day when your hands are at normal temperature, not right after exercise or in cold weather.
No — they use completely different numbering systems based on the same underlying circumference. A US size 7 is roughly an EU/ISO size 54 (or 14 on some European charts), so always convert rather than assuming the number carries over.