UK ring sizes are letters: each letter is about 0.4 mm of inner diameter, and half letters sit in between. The most common sizes are L to N for women (16.3–17.1 mm) and R to T for men (18.8–19.6 mm). UK N½ equals US 7, EU 54 and 17.3 mm. Find your letter below, or measure a ring on your phone screen and read the UK size directly.
UK ring size chart
Half letters (J½, K½ …) line up exactly with US half and whole sizes. Whole letters fall between two US sizes, so their US column shows a quarter size such as 6¼.
| UK / Australia | US / Canada | EU / ISO | Inner diameter | Inner circumference |
|---|---|---|---|---|
| F | 3 | 44 | 14.1 mm | 44.3 mm |
| G | 3.5 | 46 | 14.5 mm | 45.6 mm |
| H | 4 | 47 | 14.9 mm | 46.8 mm |
| I | 4.5 | 48 | 15.3 mm | 48.1 mm |
| J | 4¾ | 49 | 15.5 mm | 48.7 mm |
| J½ | 5 | 49 | 15.7 mm | 49.3 mm |
| K | 5¼ | 50 | 15.9 mm | 50.0 mm |
| K½ | 5.5 | 51 | 16.1 mm | 50.6 mm |
| L | 5¾ | 51 | 16.3 mm | 51.2 mm |
| L½ | 6 | 52 | 16.5 mm | 51.8 mm |
| M | 6¼ | 52 | 16.7 mm | 52.5 mm |
| M½ | 6.5 | 53 | 16.9 mm | 53.1 mm |
| N | 6¾ | 54 | 17.1 mm | 53.7 mm |
| N½ | 7 | 54 | 17.3 mm | 54.3 mm |
| O | 7¼ | 55 | 17.5 mm | 55.0 mm |
| O½ | 7.5 | 56 | 17.7 mm | 55.6 mm |
| P | 7¾ | 56 | 17.9 mm | 56.2 mm |
| P½ | 8 | 57 | 18.1 mm | 56.9 mm |
| Q | 8¼ | 57 | 18.3 mm | 57.5 mm |
| Q½ | 8.5 | 58 | 18.5 mm | 58.1 mm |
| R | 8¾ | 59 | 18.8 mm | 58.9 mm |
| R½ | 9 | 60 | 19.0 mm | 59.7 mm |
| S | 9¼ | 60 | 19.2 mm | 60.3 mm |
| S½ | 9.5 | 61 | 19.4 mm | 60.9 mm |
| T | 9¾ | 62 | 19.6 mm | 61.6 mm |
| T½ | 10 | 62 | 19.8 mm | 62.2 mm |
| U | 10¼ | 63 | 20.0 mm | 62.8 mm |
| U½ | 10.5 | 63 | 20.2 mm | 63.5 mm |
| V | 10¾ | 64 | 20.4 mm | 64.1 mm |
| V½ | 11 | 65 | 20.6 mm | 64.7 mm |
| W | 11¼ | 65 | 20.8 mm | 65.3 mm |
| W½ | 11.5 | 66 | 21.0 mm | 66.0 mm |
| X | 11¾ | 67 | 21.2 mm | 66.6 mm |
| X½ | 12 | 67 | 21.4 mm | 67.2 mm |
| Y | 12¼ | 68 | 21.6 mm | 67.9 mm |
| Z | 12.5 | 68 | 21.8 mm | 68.5 mm |
The same letter scale is used in Australia, New Zealand, Ireland and South Africa, so this chart works for shops in those countries too. Sizes below F are children’s sizes; sizes above Z are written Z+1, Z+2 and so on, and are listed in the full ring size chart.
How UK ring sizes work
The UK scale was standardised in British Standard BS 6820, which defines each letter by the inside circumference of the ring. One full letter adds about 1.25 mm of circumference (0.4 mm of diameter), and a half letter adds about 0.6 mm. That makes UK sizes slightly finer than US half sizes, which is why British jewellers often quote a half letter (for example “M and a half”) where an American shop would only offer 6.5.
A few practical points:
- Letters skip nothing. Unlike some old continental scales, every letter from A to Z is used, including I and Q.
- Z is not the end. Larger rings are written Z+1, Z+2 … each about one US half size larger.
- Half sizes are normal. High-street jewellers stock half letters for wedding bands and engagement rings; fashion rings are usually whole letters only.
UK to US ring size conversion
| UK | US | Who usually wears it |
|---|---|---|
| J – K | 4¾ – 5¼ | Petite fingers, pinky rings, midi rings |
| L – M | 5¾ – 6¼ | Slim ring fingers; very common for women |
| N – O | 6¾ – 7¼ | The middle of the women’s range |
| P – Q | 7¾ – 8¼ | Larger women’s fingers, smaller men’s |
| R – T | 8¾ – 9¾ | The most common men’s wedding band sizes |
| U – W | 10¼ – 11¼ | Larger men’s fingers, thumb rings |
| X – Z | 11¾ – 12½ | Large hands, signet rings for the little finger of big hands |
Need another system as well? The ring size converter turns any UK letter into US, EU, Indian and Swiss sizes in one step.
How to find your UK ring size at home
- On screen (quickest): open the online ring sizer, hold a bank card against the screen to calibrate, then place a ring that fits on the circle. The result shows the UK letter as well as US and EU.
- With a ring and a ruler: measure straight across the inside of the ring in millimetres and find the nearest diameter in the chart above.
- With paper or string: wrap a thin strip around the base of the finger, mark where it overlaps, and measure the length. That is the circumference column. See how to measure ring size at home for tips that stop the strip slipping.
- On paper: print the printable ring sizer on A4 at 100% and compare a ring to the true-size circles.
Buying from US or EU shops
When a UK buyer orders from an American website, convert the letter to the nearest US half size. If you are a whole letter (for example M), you sit exactly between two US sizes (6 and 6.5): choose the larger one for wide or chunky rings and the smaller one for a slim band you want to stay put. European shops use the inner circumference in millimetres, so UK N½ is simply EU 54. Swiss shops subtract 40 from that number, so N½ is Swiss 14.
Not sure of your ring size? Measure it on your phone screen in 30 seconds.
Open the free ring sizer →Related
- US ring size chart with quarter sizes
- Full ring size chart – every system on one page
- Ring size in mm
- Average ring size for women and men
Frequently asked questions
What is UK ring size N in US size?
UK N is about US 6¾ (17.1 mm inner diameter). UK N½ is exactly US 7 (17.3 mm, EU 54).
What is the most common ring size for women in the UK?
Most women in the UK wear between L and N, which is about US 5¾ to 6¾ and 16.3 to 17.1 mm inner diameter.
What is the average men's ring size in the UK?
Most men wear between R and T, about US 8¾ to 9¾ and 18.8 to 19.6 mm inner diameter.
How big is one UK ring size?
One full UK letter adds about 1.25 mm of inner circumference, or about 0.4 mm of diameter. A half letter is about 0.6 mm of circumference.
What comes after Z in UK ring sizes?
Sizes above Z are written Z+1, Z+2, Z+3 and so on. Z+1 is about US 13 (22.2 mm) and Z+3 is about US 14 (23.0 mm).