The easiest ring size conversion guide for 2026 โ convert between UK, US, Canadian, Australian, EU and mm ring sizes instantly. Full master conversion chart AโZ+2, all 5 sizing systems explained, women's and men's averages, half-size rules, and free multi-system calculator
The UK uses an alphabetical letter system running from size A (smallest) to Z+2 (largest). Each letter represents a specific finger circumference in increments of approximately 1.25mm. Used by all major British jewellers โ Goldsmiths, Beaverbrooks, H.Samuel, Ernest Jones, Tiffany UK.
Australia uses the identical AโZ+2 letter system as the UK. AU size N and UK size N are exactly the same ring โ same circumference (53.8mm), same diameter (17.1mm). No conversion needed between AU and UK. Also shared by New Zealand, South Africa and Ireland.
The US uses a numeric scale from 1 to 13.5 in half-size increments. Each US half-size equals approximately one UK letter size. Used by all major American retailers โ Tiffany US, Zales, Kay Jewellers, Brilliant Earth, Blue Nile, Amazon US, and most Etsy US sellers.
Canada uses the same 1โ13.5 numeric system as the United States. A CA size 7 ring is identical to a US size 7 ring. Conversion to UK IS required when ordering from a British jeweller. The same conversion chart and formula used for US-to-UK applies directly for CA-to-UK.
European (ISO/DIN standard) ring sizes are based on the inner circumference of the ring in millimetres โ EU size 52 means a 52mm inner circumference. Used by European retailers including Pandora EU, TJC, and most Continental and Scandinavian jewellers.
Any ring size in any system can be expressed in mm โ either as the inner diameter (measured straight across the inside of the ring) or as the inner circumference (the distance around the inside). These mm values are universal and convert directly into UK, US, EU or AU sizes using the master chart below.
Of the five ring size systems, two pairs require no conversion at all: AU = UK (same letter system) and US = CA (same numeric system). The only conversions you need to perform are between the letter system (UK/AU) and the numeric systems (US/CA and EU) โ or when working from a raw mm measurement. The master chart below handles every conversion in one table.
Find your known size in any column โ then read across the same row to find the equivalent size in every other system. The UK/AU letter column is the anchor โ every row corresponds to one UK/AU letter size. The US/CA column shows the equivalent American / Canadian number. The EU column shows the Continental size. The mm columns show the exact inner circumference and diameter for precise measurement-based conversion.
| ๐ฌ๐ง UK / ๐ฆ๐บ AU | ๐บ๐ธ US / ๐จ๐ฆ CA | ๐ช๐บ EU | Circ. (mm) | Diam. (mm) | Circ. (cm) | Circ. (inches) | Best For |
|---|---|---|---|---|---|---|---|
| A | โ | 37 | 37.8 mm | 11.9 mm | 3.78 cm | 1.488โณ | Children / XS |
| B | 1 | 38 | 39.1 mm | 12.3 mm | 3.91 cm | 1.539โณ | Children / XS |
| C | 1.5 | 40 | 40.4 mm | 12.7 mm | 4.04 cm | 1.590โณ | XS Women |
| D | 2 | 41 | 41.7 mm | 13.1 mm | 4.17 cm | 1.642โณ | Small Women |
| E | 2.5 | 42 | 42.9 mm | 13.5 mm | 4.29 cm | 1.689โณ | Small Women |
| F | 3 | 43 | 44.2 mm | 13.9 mm | 4.42 cm | 1.740โณ | Small Women |
| G | 3.5 | 45 | 45.5 mm | 14.3 mm | 4.55 cm | 1.791โณ | Women |
| H | 4 | 46 | 46.8 mm | 14.7 mm | 4.68 cm | 1.843โณ | Women |
| I | 4.5 | 47 | 48.0 mm | 15.1 mm | 4.80 cm | 1.890โณ | Women |
| J | 4.75 | 48 | 48.7 mm | 15.5 mm | 4.87 cm | 1.917โณ | Women |
| K | 5 | 49 | 50.0 mm | 15.9 mm | 5.00 cm | 1.969โณ | Women |
| L | 5.5 | 50 | 51.2 mm | 16.3 mm | 5.12 cm | 2.016โณ | Women |
| M | 6 | 51 | 52.5 mm | 16.7 mm | 5.25 cm | 2.067โณ | Women |
| N โญ | 6.5 | 52 | 53.8 mm | 17.1 mm | 5.38 cm | 2.118โณ | Women's Avg โญ |
| O โญ | 7 | 54 | 55.1 mm | 17.5 mm | 5.51 cm | 2.169โณ | Women Popular |
| P โญ | 7.5 | 55 | 56.3 mm | 17.9 mm | 5.63 cm | 2.217โณ | Women Popular |
| Q | 8 | 57 | 57.6 mm | 18.2 mm | 5.76 cm | 2.268โณ | Slim Men |
| R | 8.5 | 58 | 58.9 mm | 18.6 mm | 5.89 cm | 2.319โณ | Lean Men |
| S | 9 | 60 | 60.2 mm | 19.1 mm | 6.02 cm | 2.370โณ | Avg Slim Men |
| T โญ | 9.5 | 61 | 61.4 mm | 19.56 mm | 6.14 cm | 2.417โณ | Men's Avg โญ |
| U โญ | 10 | 63 | 62.7 mm | 19.96 mm | 6.27 cm | 2.469โณ | Men Popular |
| V โญ | 10.5 | 64 | 64.0 mm | 20.37 mm | 6.40 cm | 2.520โณ | Men Popular |
| W | 11 | 65 | 65.3 mm | 20.78 mm | 6.53 cm | 2.571โณ | Athletic Men |
| X | 11.5 | 67 | 66.6 mm | 21.18 mm | 6.66 cm | 2.622โณ | Broad Men |
| Y | 12 | 68 | 67.8 mm | 21.59 mm | 6.78 cm | 2.669โณ | Large Build |
| Z | 12.5 | 69 | 68.5 mm | 21.79 mm | 6.85 cm | 2.697โณ | XL Build |
| Z+1 | 13 | 70 | 69.7 mm | 22.20 mm | 6.97 cm | 2.744โณ | XL Custom |
| Z+2 | 13.5 | 72 | 72.3 mm | 23.01 mm | 7.23 cm | 2.846โณ | Custom |
Because UK/AU sizes are letters, enter the position of the letter in the alphabet as a number for the calculator โ for example: N = 14, O = 15, P = 16, T = 20, U = 21, V = 22. Z = 26, Z+1 = 27, Z+2 = 28. Alternatively, use the US/CA or EU input with your known equivalent size โ the result will show the UK letter automatically. For the most direct lookup, use the master chart above and read across the row.