Free sizing tool
Find Your Ring Size
Estimate your ring size at home by measuring a ring you already own or your finger. The result is an estimate only — always confirm the final size with the retailer before ordering.
Estimate only. This tool provides an estimate only. Screen settings, measurement technique, ring width, and finger temperature can affect the result. Confirm your size with the retailer before ordering.
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Tips for a better estimate
- Measure at room temperature.
- Measure more than once and compare results.
- Measure in the evening, when fingers may be slightly larger.
- Wider bands may feel tighter than thin ones.
- If you are between sizes, confirm with the retailer.
- Do not use this tool as a medical or professional measurement device.
How the ring size calculator works
Screens differ in size and pixel density, so the tool first asks you to match an on-screen rectangle to a real bank card, which has a standard size of 85.6 × 53.98 mm. That tells the tool how many screen pixels make up one millimetre on your device. It then turns your measurement into an inner diameter and finds the closest standard size in our conversion chart.
How to measure an existing ring
Choose a ring that fits the intended finger comfortably. Hold it flat against the screen and resize the circle until its outer edge meets the inside edge of the band — not the outside. Measure the inner edge only, and check from directly above to avoid angle errors.
How to measure your finger at home
Wrap a thin strip of paper or non-stretchy string snugly around the base of the finger. Mark where the end overlaps, lay it flat against a ruler, and read the length in millimetres. If your knuckle is larger than the base of your finger, measure the knuckle too and use the larger number so the ring can slide on.
How US, UK, and EU ring sizes differ
US and Canadian sizes use numbers with half sizes (for example 6 or 6½). UK and Australian sizes use letters, sometimes with halves (for example L½). EU sizes broadly follow the inner circumference in millimetres (for example 52). The systems do not line up exactly, so conversions are approximate.
For more on fit and surprise proposals, read how to find a ring size, explore the engagement ring guide, learn the basics in the Ring Wisdom, or browse our comparisons.
Frequently asked questions
How accurate is the calculator?
It gives an estimate. Accuracy depends on careful screen calibration, how precisely you line up the ring or measure your finger, and the band width. Treat the result as a starting point and confirm your size with the retailer before ordering.
Can I use the calculator on a phone?
Yes. Calibrate first by matching the on-screen card to a real bank card, then measure. Larger screens make it easier to line things up, but a phone works if you calibrate carefully.
What if I do not have a ring to measure?
Choose “Measure your finger”. Wrap a thin strip of paper or non-stretchy string around the base of the finger, mark where it overlaps, measure that length in millimetres with a ruler, and enter it.
What if I am between sizes?
The tool shows the closest size and the two sizes either side. Many people choose the larger size for comfort, especially for wider bands, but confirm with the retailer — many offer sizing advice or resizing.
Does ring width affect fit?
Yes. Wider bands cover more of the finger and usually feel tighter than a thin band of the same size, so some people size up slightly for a wide band.
Can finger size change during the day?
Yes. Fingers are often slightly larger in the evening and in warm weather, and smaller when cold. Measuring a few times at room temperature gives a more reliable estimate.
Ring Wisdom does not collect or store your measurements. Everything is calculated in your browser and disappears when you leave the page.