Ring Size Calculator

Three home methods. First: wrap a strip of paper around your finger snugly, mark where it overlaps, measure that length in mm — that's your circumference. Second: use a piece of string the same way, then measure against a ruler. Third: measure the inside diameter of a ring that already fits well. Use a ring size chart to convert. Don't measure cold fingers (they shrink); measure when fingers are at normal temperature. Knuckles are wider than the base — measure both, and pick a size that slides over the knuckle but doesn't slip off. Ideally measure 2–3 times for consistency.

US ring sizes correspond to inside circumference in mm. Quick reference: 44 mm = US 3, 47 mm = US 4, 50 mm = US 5.5, 52 mm = US 6, 54 mm = US 7, 57 mm = US 8, 59 mm = US 9, 62 mm = US 10. Each US half-size is about 1 mm of circumference. Convert by checking a chart for your exact mm value. Calculators do this instantly. The US system uses different numbers than UK or EU, even for the same physical ring. Always specify which system when ordering — a 'size 7' means different things in different countries.

US to UK: roughly subtract 0.5 to 1 to get the UK letter equivalent. US 6 ≈ UK L. US 7 ≈ UK N. US 8 ≈ UK P. US 9 ≈ UK R. UK uses letters; US uses numbers. EU uses circumference in mm directly: US 6 ≈ EU 52, US 7 ≈ EU 54, US 8 ≈ EU 57, US 9 ≈ EU 59. Conversion charts vary slightly between brands. For online purchases from the UK or EU, double-check the chart on the seller's website. Slight differences (half a size) matter when ordering an expensive ring.

Fingers are larger in the evening than morning due to fluid retention from heat, salt, and activity. Measure in the late afternoon or early evening for a size that fits comfortably most of the day. Morning measurements often give a tight fit that becomes uncomfortable later. Avoid measuring after exercise (fingers swell) or in cold weather (fingers shrink). For wedding rings or rings you'll wear daily, consistent comfort matters. If your fingers swell significantly during summer or pregnancy, choose the larger size of any borderline result. The right ring slides on smoothly and rotates slightly without falling off.

Wider rings cover more skin, so they grip the finger more firmly. A 4 mm wide ring at size 7 may fit comfortably; an 8 mm wide ring at the same size 7 feels tighter. The general rule: for rings wider than 6 mm, go up half a size. For rings 8 mm or wider (men's wedding bands often), go up a full size. The pressure distributes differently, so the same physical inside diameter feels different depending on band width. When buying wide rings, try a half-size up first, or order both and choose the better fit.

Choose the larger size, especially for daily wear. Fingers swell in heat, after meals, and during the day, so the slightly larger size remains comfortable. For wedding rings or rings you can't easily resize without damage, the larger size is safer. For occasional jewellery or rings you can adjust, the smaller size is fine if it fits over the knuckle. Most jewellers can resize rings up or down by half a size without difficulty; larger adjustments are harder and may affect engraving or stones. Sizing up is easier than sizing down typically. When in doubt, go larger.