How to Measure Your Ring Size — With a Paper Strip, a Ring You Own, or an On-Screen Circle
Three ways to measure your ring size at home without going to a shop (paper strip, inner diameter of an existing ring, actual-size circle on screen), and tips for reducing error.
One ring size step is only about 1 mm of circumference. Rings become tight or loose with much smaller differences than shoes or clothes, so it is important to measure several times under consistent conditions.
Method 1. Measure the circumference with a paper strip
- Cut a paper strip about 5 mm wide and 10 cm long. String stretches and gives large errors, so paper or a thin plastic strip is better.
- Wrap the strip around the finger you will wear the ring on. Wrap it where the ring will sit, not over the knuckle it has to pass, and don't pull it too tight.
- Mark the point where the strip overlaps with a fine pen.
- Unroll the strip and measure from the end to the mark in mm. This value is the inner circumference.
- In the converter's ‘Rings’ tab, choose ‘Circumference’ under ‘Find by finger measurement’ and enter the value.
If your knuckles are large, the ring has to pass over them, so measure your knuckle as well and choose a size between the two values (closer to the knuckle).
Method 2. Measure the inner diameter of a ring that fits
If you already have a ring that fits that finger well, this is the most accurate method.
- Place the ring on paper and lay a ruler across its widest part, from inner edge to opposite inner edge.
- Leave out the thickness of the metal and measure only the inside. Even 0.5 mm is close to one full size.
- Choose ‘Inner diameter’ in the converter and enter the value. Inner diameter × 3.14 is the circumference.
Method 3. Compare with the actual-size circle on screen
The converter draws the inner diameter of the selected size on screen at actual size. However, the number of pixels in 1 mm differs from device to device, so calibration is needed first.
- Get a credit card or debit card. A card of the international format (ISO/IEC 7810 ID-1) is 85.6 mm wide.
- Hold the card against the dashed box on screen and move the slider until the widths match exactly.
- Place a ring you own on the circle on screen and find the size whose line matches its inner edge.
The calibration is saved only in that device's browser. If you change the screen zoom level, calibrate again.
Tips for reducing error
- Measure in the afternoon, at room temperature. Fingers get thinner in the cold and swell after heat, exercise or salty food.
- Measure two or three times at different times and use a value close to the average.
- Fingers on your dominant hand are often slightly thicker. Measure the exact finger you will wear the ring on.
- Wide rings (roughly 6 mm or more) feel tighter at the same size, so people often choose half to one size larger.
After choosing a size
Ring systems have different steps. One US size is about 2.55 mm of circumference, one UK letter is 1.25 mm, one Japanese or Korean size is about 1 mm, and Europe (ISO) is 1 mm. If you know the circumference, you can find the closest value in the ring size chart. If it is a gift and hard to measure in secret, the safest option is to check first whether the size can be exchanged.
Size systems are approximate correspondences based on national standards and industry practice, and can differ by half to one size depending on brand, product and fabric. Always check the brand's own size chart before buying.