Ring Size Calculator & Guide
Instantly convert your ring circumference or diameter to UK, US, and EU ring sizes. Perfect for online jewellery shopping and gift-giving.
Find Your Perfect Ring Size
Enter your finger measurement below to instantly see your corresponding ring size across major international sizing standards.
Ring Size Converter
Get your UK, US, and EU size based on your measurement.
How to Measure Accurately
Follow these steps for reliable results
The String Method
Wrap a non-stretchy piece of string or a thin strip of paper around the base of your finger. Mark where the ends overlap, then measure the length in mm with a ruler.
The Existing Ring Method
Place a ring that already fits the intended finger perfectly flat on a ruler. Measure the internal diameter (inside edge to inside edge) in millimetres.
Consider the Knuckle
If your knuckle is significantly larger than the base of your finger, measure both. Choose a size halfway between the two to ensure the ring can slide on comfortably.
Account for Ring Width
Wider bands (over 6mm) fit more snugly. If you are buying a wide band, consider going up a half or full size from your standard measurement.
International Size Chart
Standardised approximate conversions for ring sizes across major regions.
| UK Size | US Size | EU Size | Diameter (mm) | Circumference (mm) |
|---|---|---|---|---|
| 3 | 44 | 14.1 | 44.2 | |
| 3.5 | 45.2 | 14.5 | 45.5 | |
| 4 | 46.5 | 14.9 | 46.8 | |
| 4.5 | 47.8 | 15.3 | 48.0 | |
| 5 | 49.0 | 15.7 | 49.3 | |
| 5.5 | 50.3 | 16.1 | 50.6 | |
| 6 | 51.5 | 16.5 | 51.9 | |
| 6.5 | 52.8 | 16.9 | 53.1 | |
| 7 | 54.0 | 17.3 | 54.4 | |
| 7.5 | 55.3 | 17.7 | 55.7 | |
| 8 | 56.6 | 18.1 | 57.0 | |
| 8.5 | 57.8 | 18.5 | 58.3 | |
| 9 | 59.1 | 18.9 | 59.5 | |
| 9.5 | 60.3 | 19.3 | 60.8 | |
| 10 | 61.6 | 19.7 | 62.1 | |
| 10.5 | 62.8 | 20.1 | 63.4 | |
| 11 | 64.1 | 20.5 | 64.6 | |
| 11.5 | 65.3 | 20.9 | 65.9 | |
| 12 | 66.6 | 21.3 | 67.2 | |
| 12.5 | 67.8 | 21.7 | 68.5 | |
| 13 | 69.1 | 22.1 | 69.7 |
Ring Size FAQ
Answers to the most frequently asked questions about measuring fingers and converting jewellery sizes.
The most accurate method is to wrap a non-stretchy piece of string or a thin strip of paper around the base of your finger, mark where the ends overlap, and measure the length in millimetres with a ruler. Alternatively, measure the internal diameter of a ring that already fits you well.
Measure both the base of your finger and your knuckle. Choose a ring size that falls between the two measurements. This ensures the ring can slide over your knuckle comfortably but won’t spin loosely once it is in place.
Yes. The UK and Australia use an alphabetical system (e.g., size L, M, N). The US and Canada use a numerical system (e.g., size 6, 7, 8). Europe uses a numerical system based directly on the inner circumference in millimetres (e.g., size 52, 54).
Fingers can swell in hot weather or after physical activity, and shrink in cold weather. For the most accurate and consistent result, measure your finger at room temperature at the end of the day, when your fingers are typically at their largest.
Yes. Wider bands (typically over 6mm) cover more of the finger and fit more snugly. If you are purchasing a wide or chunky ring, it is generally recommended to go up a half or full size from your standard measurement for a comfortable fit.