Ring Size Converter → How to measure ring size
How to measure your ring size at home
You don't need a jeweler or a special tool. Here are three accurate at-home methods — pick one, then drop the number into the converter to get your size in every standard.
Method 1 — Measure a ring that already fits (most accurate)
Take a ring that fits the intended finger and measure straight across the insidewith a millimeter ruler — that's the inside diameter. A typical women's ring is about 15–18 mm across; men's about 18–21 mm. Enter it in the converter below (Inside diameter tab).
Method 2 — Wrap your finger with paper or string
- Cut a thin strip of paper, or use a piece of string.
- Wrap it snugly around the base of your finger, where the ring will sit.
- Mark where it overlaps, then lay it flat on a ruler and read the length in millimeters.
- Enter that number in the converter (Finger circumference tab).
Method 3 — Measure on your screen
No ruler at all? The on-screen ring sizer lets you calibrate to a bank card and lay a ring over an actual-size circle to read the size directly.
Find your size now
Enter a measurement above to see your size in every standard.
Tips for an accurate measurement
- Time it right. Measure late in the day at normal body temperature — fingers swell and shrink.
- Mind the knuckle. The ring must slide over your knuckle. If your knuckle is much larger than the base, size to something in between.
- Wide bands run snug. Add a quarter–half size for bands wider than ~6 mm.
- Between sizes? Round up. A slightly loose ring is easily resized; a too-tight one isn't.
- Measure twice. Take a few readings on different days and trust the largest.
Frequently asked questions
How can I measure my ring size at home without a sizer?
Two reliable ways with things you already have. (1) Wrap a strip of paper or string around the base of your finger, mark where it overlaps, and measure that length in millimeters — that's your circumference. (2) Measure the inside diameter of a ring that already fits with a millimeter ruler. Enter either number into the converter on this page.
How do I measure my ring size with a tape measure?
Use a soft/fabric tape measure or a strip of paper. Wrap it snugly around the base of the finger (below the knuckle, where the ring sits), note the millimeter mark where it meets, and enter that as your finger circumference. If the tape only shows inches, switch the converter to inches.
How do I figure out someone's ring size secretly?
Borrow a ring they already wear on that finger and measure its inside diameter, or press it into a bar of soap and measure the imprint. You can also trace the inside of the ring on paper. Compare against the chart. If you can't borrow one, ask a friend or note a ring's size the next time it's off.
What is the best time of day to measure ring size?
Late afternoon or evening, when your body is at normal temperature. Fingers shrink when cold and swell in heat, after salty food, and during exercise. Measure a few times across different days and use the largest reading for everyday comfort.
Should I size up for a wide band?
Yes. Wide bands (over ~6 mm) sit more snugly, so go up a quarter to a half size versus a thin band. When you're between sizes, round up.