💍 What Is An International Ring Size Converter?
An international ring size converter helps you compare ring sizing systems used in different countries. A ring listed as a UK letter size may be shown as a number in the United States or Canada and as a different numerical size in Europe. The converter below compares these systems against the ring's physical inside diameter and circumference.
This is especially useful when buying jewellery online from an overseas store, checking an engagement ring size, comparing a designer's chart, or converting a ring size supplied by a friend or family member abroad.
International conversions should be treated as close equivalents rather than guaranteed identical sizes. Retailers can round measurements differently, so always check the seller's own ring size chart before placing an important order.
Convert Your Ring Size Instantly
Choose the sizing system, enter a size or measurement, and get the nearest international match.
Tip: for letter sizes, enter values such as N, N½ or Z+1. For numeric systems, use digits such as 6.5 or 54.
UK Ring Sizes
Letter-based sizing such as K, L, M, N and O, often with half sizes.
US / Canada Sizes
Numerical sizing with full, half and sometimes quarter-size increments.
European Sizes
Numerical sizing commonly related to the ring's inside circumference in millimetres.
Physical Measurements
Diameter and circumference provide the most useful cross-system comparison.
Physical measurements connect different sizing systems
The same ring opening can be labelled differently in the UK, US and Europe.
1. UK Letter
British jewellery usually uses letter sizes. Half sizes may appear as N½ or similar.
2. US Number
North American sizing uses numbers. The nearest match may not align perfectly with every UK half size.
3. EU Number
European sizing is often close to an inside-circumference reference, making millimetres useful for comparison.
| UK | US / Canada | EU | Diameter | Circumference |
|---|---|---|---|---|
| UK A | 0.5 | — | 12.04 mm | 37.8 mm |
| UK A½ | 0.75 | — | 12.24 mm | 38.5 mm |
| UK B | 1 | — | 12.45 mm | 39.1 mm |
| UK B½ | 1.25 | — | 12.65 mm | 39.7 mm |
| UK C | 1.5 | — | 12.85 mm | 40.4 mm |
| UK C½ | 1.75 | — | 13.06 mm | 41.0 mm |
| UK D | 2 | 41.5 | 13.26 mm | 41.7 mm |
| UK D½ | 2.25 | 42 | 13.46 mm | 42.3 mm |
| UK E | 2.5 | 42.75 | 13.67 mm | 42.9 mm |
| UK E½ | 2.75 | 43.5 | 13.87 mm | 43.6 mm |
| UK F | 3 | 44 | 14.07 mm | 44.2 mm |
| UK F½ | 3.2 | 44.75 | 14.27 mm | 44.8 mm |
| UK G | 3.375 | 45.25 | 14.48 mm | 45.5 mm |
| UK G½ | 3.6 | 46 | 14.68 mm | 46.1 mm |
| UK H | 3.75 | 46.5 | 14.88 mm | 46.8 mm |
| UK H½ | 4 | 47.25 | 15.09 mm | 47.4 mm |
| UK I | 4.25 | 47.75 | 15.29 mm | 48.0 mm |
| UK J | 4.625 | 49 | 15.49 mm | 48.7 mm |
| UK J½ | 4.875 | 49.5 | 15.70 mm | 49.3 mm |
| UK K | 5.125 | 50 | 15.90 mm | 50.0 mm |
| UK K½ | 5.25 | 50.5 | 16.10 mm | 50.6 mm |
| UK L | 5.5 | 51.75 | 16.31 mm | 51.2 mm |
| UK L½ | 5.75 | 52 | 16.51 mm | 51.9 mm |
| UK M | 6 | 52.75 | 16.71 mm | 52.5 mm |
| UK M½ | 6.25 | 53.25 | 16.92 mm | 53.1 mm |
| UK N | 6.5 | 54 | 17.12 mm | 53.8 mm |
| UK N½ | 6.75 | 54.5 | 17.32 mm | 54.4 mm |
| UK O | 7 | 55.25 | 17.53 mm | 55.1 mm |
| UK O½ | 7.25 | 55.75 | 17.73 mm | 55.7 mm |
| UK P | 7.5 | 56.5 | 17.93 mm | 56.3 mm |
| UK P½ | 7.75 | 57 | 18.14 mm | 57.0 mm |
| UK Q | 8 | 57.75 | 18.34 mm | 57.6 mm |
| UK Q½ | 8.25 | 58.25 | 18.54 mm | 58.3 mm |
| UK R | 8.625 | 59 | 18.75 mm | 58.9 mm |
| UK R½ | 8.875 | 59.5 | 18.95 mm | 59.5 mm |
| UK S | 9.125 | 60.25 | 19.15 mm | 60.2 mm |
| UK S½ | 9.375 | 60.75 | 19.35 mm | 60.8 mm |
| UK T | 9.625 | 61.5 | 19.56 mm | 61.4 mm |
| UK T½ | 9.875 | 62 | 19.76 mm | 62.1 mm |
| UK U | 10.25 | 62.75 | 19.96 mm | 62.7 mm |
| UK U½ | 10.375 | 63.25 | 20.17 mm | 63.4 mm |
| UK V | 10.625 | 63 | 20.37 mm | 64.0 mm |
| UK V½ | 10.875 | 64.5 | 20.57 mm | 64.6 mm |
| UK W | 11.125 | 65 | 20.78 mm | 65.3 mm |
| UK W½ | 11.375 | 65.5 | 20.98 mm | 65.9 mm |
| UK X | 11.625 | 66.25 | 21.18 mm | 66.6 mm |
| UK X½ | 11.875 | 67 | 21.39 mm | 67.2 mm |
| UK Y | 12 | 67.5 | 21.59 mm | 67.8 mm |
| UK Z | 12.5 | 68.75 | 21.79 mm | 68.5 mm |
| UK Z½ | 12.75 | 69.25 | 22.00 mm | 69.1 mm |
| UK Z+1 | 13.5 | 71 | 22.61 mm | 71.0 mm |
| UK Z+2 | 14 | 72.25 | 23.01 mm | 72.3 mm |
| UK Z+3 | 14.25 | 73 | 23.22 mm | 72.9 mm |
| UK Z+4 | 15 | 74.25 | 23.62 mm | 74.2 mm |
Note: International values are approximate equivalents. Some brands use their own rounding, quarter sizes or proprietary fit guidance.
UK Ring Size System
The British system normally uses letters rather than numbers. Sizes progress through the alphabet and many jewellers also offer half sizes. When a UK letter is unfamiliar to an overseas seller, diameter or circumference can provide a clearer reference.
US & Canada Ring Sizes
The United States and Canada generally use numerical ring sizes. Full and half sizes are widely used, while some jewellers also offer quarter sizes. A UK size can therefore fall between two North American labels.
European Ring Sizes
European ring sizing commonly uses numerical values associated with metric measurements. This makes circumference especially useful when comparing a European chart against UK or US sizing.
Why Conversions Differ
Published charts may use slightly different rounding, tolerance and manufacturing assumptions. Ring width, comfort-fit profiles and resizing policies can also affect the final recommended size.
Measure the exact finger
Use the hand and finger on which the ring will actually be worn. The same finger on opposite hands may not be identical.
Use an existing ring where possible
A ring that already fits can provide a useful inside-diameter measurement. Measure straight across the empty centre.
Measure in millimetres
Metric measurements are easier to compare against international charts. If you only have inches, the converter can handle them too.
Compare more than one reference
Check the converter result against the retailer's own chart, especially when buying an expensive, wide or hard-to-resize ring.
- 📐Prioritise diameter or circumference when the seller provides physical measurements.
- 🌡️Measure at a normal room temperature because finger size can change with heat and cold.
- 💍Ask whether a wide band needs a different size from a narrow ring.
- 📦Check the overseas retailer's exchange, resizing and returns policy before ordering.
- 🔁Take several measurements and use a consistent reading rather than one quick measurement.
- 🏪For engagement rings, wedding rings and luxury jewellery, confirm your result with a professional jeweller.