Ring Sizer & Size Converter

Find your ring size on your phone, no camera and no tape measure.

Hold a bank card against the screen once to calibrate, then lay a ring you own flat on the display and slide the circle until it fits inside the band. The size appears straight away in US and Canada, UK and Australia, EU (ISO circumference) and Japan.

Or just type it in
Enter the inside diameter of a ring in millimetres, or the circumference of a finger, and read the size in every system at once.

Why calibrate?
Screens are different sizes and densities, so a circle drawn at a fixed number of pixels is only right on one phone. Every bank card is the same width the world over, which gives the app a real ruler to measure your own screen against.

SIZES BOOK (one-time unlock)
Save sizes for a partner, family or a gift you are planning, each with a name. Get a suggested size for wide bands, which fit tighter than thin ones.

The gauge and every conversion are free, always.

No account. No camera. Saved sizes stay on your phone.

Recent changes:
Match a ring to the circle on your screen and read the size in US, UK, EU and Japanese systems. Free, no camera, no account.