Measure Ring Size

Method

Measure ring size with a tape measure

A flexible sewing tape, wrapped around the finger and read in millimetres, is the best finger-only method at home. It reads circumference directly — no marking, no second ruler step, and no stretch if the tape is the right kind.

What you need

A flexible tape

A soft sewing tape, the kind that rolls up. It must bend around the finger without resisting. A metal builder's tape does not count: it is too stiff to wrap, and its hook adds millimetres you cannot see.

Millimetres on the tape

Read the millimetre side, not the inch side. A half-size step is about 1.3 mm of circumference, so a reading to the nearest millimetre is the minimum that is useful — whole centimetres are not.

The right finger, in the evening

The exact finger, on the exact hand, measured in the evening when the finger is at its largest. A morning reading is the classic way to buy a ring that will not go on at night.

Step by step

  1. Wrap at the base of the finger

    Wrap the tape around the base of the finger, where the ring will sit — not over the knuckle, unless the knuckle is wider than the base (see below). Keep the tape flat against the skin, not twisted.

  2. Snug, not tight

    Pull until the tape touches all the way around with no gap, then stop. It should feel like a ring that fits, not like a tourniquet. If the skin bulges either side of the tape, you have pulled too hard and the reading will be too small.

  3. Read where the tape meets itself

    Read the number at the point where the end of the tape meets the wrapped tape. That number, in millimetres, is the finger's circumference. Write it down before you unwrap — a second wrap rarely gives the identical number, and you want the first one.

  4. Repeat once, and check the knuckle

    Wrap a second time. If the two readings differ by more than 1 mm, wrap a third time and take the middle value. Then wrap once around the knuckle: if the knuckle reading is larger, size for the knuckle, or the ring will not go on at all.

  5. Convert the number

    Type the circumference into the calculator below. It matches the nearest chart row and shows every system — no formula, the published table.

Convert your tape measurement

Decimal numbers are welcome. Use a dot for decimals, for example 16.5.

What you measured

Circumference

Changing the unit reinterprets the number you typed in the new unit — it does not convert it. Re-enter the number if you measured in a different unit.

Note: Tension: snug, not tight — the strip should slide over the knuckle with slight resistance, and should not dent the finger. Knuckle: if your knuckle is wider than the finger base, size for the knuckle, or the ring will not go on. Measure in the evening, with warm hands, and repeat twice, taking the largest reading.

Try an example

Highlight my country's size

Enter a measurement to see your size.

Formulas: circumference = π × diameter; diameter = circumference ÷ π. Matching uses your full, unrounded value; displayed diameter is rounded to 2 decimal places and circumference to 1 decimal place.
Three steps: wrap a flexible tape snugly at the base of the finger, read where it meets itself, repeat and check the knuckle
Flexible-tape method, step by step. Follow the written steps above; do not compress the finger, and never use this diagram's dimensions as a measurement.

Tape mistakes, specifically

  • A stretched-out old tape. Fabric tapes stretch with age and washing. If your tape is years old, check it against a ruler: 100 mm on the tape must be 100 mm on the ruler. A stretched tape reads large, so the ring comes out too big.
  • Reading the inch side and converting roughly. 2⅛ inches is not 54 mm — it is 53.98 mm, and that 0.02 mm is fine, but rounding 2.14 inches to 2 inches loses 3.5 mm, which is nearly three half-sizes. Always read the millimetre side.
  • Measuring over a bent finger. A bent finger is wider at the joint. Keep the finger straight and relaxed, hand at rest, not clenched and not stretched out stiffly.
  • One reading only. Tape readings vary by a millimetre or two between wraps. One reading is a guess with a number attached; two or three readings are a measurement.
Note: Tape vs. paper strip vs. string: tape wins because it skips the mark-and-measure step, where most strip and string error creeps in. If you do not have a flexible tape, the paper-strip method on the finger page is the next best option — string is last, because it stretches.

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