US Ring Size to UK: Two-Way Chart from I/US 4 to Z+7/US 16
To convert a US ring size to UK, read straight across our chart: US 4 is a UK I, US 6 is M, US 7 is O, US 8 is Q, US 10 is U, and the scale runs on to US 16 at Z+7. These are the pairs in our size menu, so what you look up is exactly what you order.
The chart is the same for men and women. Width, knuckles and what to do if the size turns out wrong are dealt with below.
In This Guide
- US Ring Size to UK Conversion Chart (I/US 4 to Z+7/US 16)
- Ring Sizes UK to US and Back: How to Read the Chart Both Ways
- What UK Ring Size Is Above Z, and What Is It in US Sizes?
- Does Band Width Affect Ring Size When Converting US to UK?
- What Happens If the Ring Size Is Wrong? Exchanges, Sets and Delivery
- Conclusion
US Ring Size to UK Conversion Chart (I/US 4 to Z+7/US 16)
US 4 is a UK I, and from there each full UK letter pairs with a US half-size step up to Z at US 12.5, then Z+1 to Z+7 cover US 13 to US 16. Find your size in either column and read across.
| UK size | US size |
|---|---|
| I | 4 |
| J | 4.5 |
| K | 5 |
| L | 5.5 |
| M | 6 |
| N | 6.5 |
| O | 7 |
| P | 7.5 |
| Q | 8 |
| R | 8.5 |
| S | 9 |
| T | 9.5 |
| U | 10 |
| V | 10.5 |
| W | 11 |
| X | 11.5 |
| Y | 12 |
| Z | 12.5 |
| Z+1 | 13 |
| Z+2 | 13.5 |
| Z+3 | 14 |
| Z+4 | 14.5 |
| Z+5 | 15 |
| Z+6 | 15.5 |
| Z+7 | 16 |
We chose these pairs from experience fitting our comfort-fit bands, which is why they differ slightly from generic UK/US conversion charts, including the general international table on our Ring Size Chart page. If you need EU, Japanese or millimetre sizes, use that page rather than mixing systems here. If you are ordering from us, use the table above.
If you only know your size roughly, our ring sizer tool covers US 2 to 13. The individual sizes detach, so you can wear the one that feels right for a few hours, then read across to the UK letter. If you don't know your size at all, choose the free ring sizer option in the size menu and we'll send one before your ring; the free international ring sizer page explains how that works.
Ring Sizes UK to US and Back: How to Read the Chart Both Ways
Read the chart left to right for UK to US and right to left for US to UK: US 6 is a UK M, US 7 is O, US 8 is Q and US 10 is U. Going the other way, UK M is US 6, UK S is US 9 and UK W is US 11.
The two systems label the same finger differently. The US uses numbers in quarter steps (7, 7.25, 7.5), while the UK works through the alphabet (N, O, P). Neither is bigger than the other; they are two scales laid over one measurement, so a US 7 and a UK O describe the same finger.
What does differ is the step. The gap between neighbouring UK letters is smaller than the gap between whole US numbers, which is why one letter step lines up with a US half size in our menu rather than a full size.
Generic charts also show UK half sizes such as L½ or N½. Our menu steps in whole letters paired to US half sizes, so if you've been told you're an L½, the honest answer is that you sit between L and M. The difference between those two is a fraction of a millimetre, which is exactly why guessing is unreliable: try both on a sizer and keep the one that passes the knuckle with a little resistance.
For a slim band, the 4mm metal ring sizer is the right tool for a borderline size. It is solid stainless steel with the same gently domed comfort-fit interior as our finished bands, so what you feel on the sizer is what you'll feel on the ring (see our guide to UK sizes and mm conversions for the measurement behind each letter).
What UK Ring Size Is Above Z, and What Is It in US Sizes?
Above Z, UK sizing continues as Z+1, Z+2 and so on. In our size menu those sizes pair with US sizes like this:
- Z+1 / US 13
- Z+2 / US 13.5
- Z+3 / US 14
- Z+4 / US 14.5
- Z+5 / US 15
- Z+6 / US 15.5
- Z+7 / US 16
Most UK charts stop at Z, or show a vague Z½, which leaves anyone with larger hands guessing. The UK scale formally runs A to Z and is extended with these numerical additions; the US adult scale carries on into the mid-teens, historically to 16, so the two line up well past the point where generic charts fade out.
Larger sizes are common for men's bands, particularly wider ones. If you measure as a US 13, look for Z+1 in our size menu, not Z: Z is a US 12.5 in our pairing, and half a size on a wide tungsten band is noticeable.
Two practical notes. Not every ring is offered in every plus size, so check the menu on the product page for the design you like. And the ring sizer tool covers US 2 to 13 only, so if you expect to be above that, choose the free ring sizer option in the size menu or use a metal sizer in the width you plan to buy.
The Farrier is the sort of band where plus sizes matter: 8mm wide, tungsten carbide with rose gold and black plating, a flat profile outside and a comfort-fit curve inside.
Does Band Width Affect Ring Size When Converting US to UK?
No, the size label stays the same, but width changes how that size feels. A 4mm band covers a narrow strip of finger and settles into the crease at the base; an 8mm band in the same size covers twice as much skin, has nowhere to settle and feels snugger. If you're moving from a slim band to a wide one, test rather than assume.
All our metal bands have a comfort-fit profile: the interior is gently domed rather than a flat pipe, so the ring eases over the knuckle and sits with less contact at the edges.
The reliable way to settle width is to measure with a sizer that matches the width you intend to buy. A wide gauge used for a thin ring gives a loose result, and a thin gauge for a wide ring gives a tight one.
| Sizer | Width | Material | Interior | Suits |
|---|---|---|---|---|
| 4mm metal ring sizer | 4mm | Solid stainless steel | Gently domed comfort fit | Slim bands |
| 6mm metal ring sizer | 6mm | Solid stainless steel | Gently domed comfort fit | Medium bands |
| 8mm metal ring sizer | 8mm | Solid stainless steel | Gently domed comfort fit | Wide bands |
Each sizer has the same interior as our finished bands and a plain polished exterior with no inlay, so you concentrate on fit rather than looks. Wear it for a few hours through normal activity: typing, washing up, a walk.
Check fit at a neutral temperature
Fingers swell in heat and after exercise and shrink in the cold. Measure in a normal room, not straight after a run or a winter walk, and ideally later in the day when hands are at their fullest.
The ring should pass over the knuckle with slight resistance and not spin freely at the base. Size the exact finger you'll wear it on; the dominant hand is usually slightly larger, so a measurement from the other hand can be out by a size.
One honest trade-off with tungsten, titanium and black zirconium: they do not flex, stretch or mould to the finger, so the size you choose is the size you live with. A loose ring spins and a tight one restricts. Our sizers are in the ring sizers collection, and our comparison of metal and plastic sizers explains the difference between the two tools.
What Happens If the Ring Size Is Wrong? Exchanges, Sets and Delivery
If the size is wrong, you have a 90-day size exchange. The details are in our Refunds & Returns policy, and the 90 day size exchange page sets out how to arrange one. Getting the size right first still saves you the return post, which is why we'd rather you spent an evening with a sizer.
Every ring arrives with a complimentary silicone ring and a ring box. The silicone ring is handy on the finger while an exchange is being sorted, and afterwards for the gym or the garden. If you'd like a second one to stack, the 3mm Granite Grey braided silicone ring sits neatly beside a metal band.
On timing: we aim to dispatch in-stock rings within a week. A ring not in stock takes 2–8 weeks, or up to 12 weeks for a solid meteorite ring (rings with meteorite shavings set in resin take the usual 2–8 weeks).
Our guide to matching wedding rings covers couples sets, which are labelled Ring 1 / Ring 2 in fixed width pairings such as 4mm & 6mm, with each ring sized separately. One partner can order a US 9 and the other a UK L, each converting their own size from the chart above, and the set still arrives as a pair.
We ship worldwide: UK, Europe, Australia, New Zealand and the rest of the world, with European and rest-of-world orders going by Royal Mail. EU orders are sent duties paid; Australian and New Zealand orders are not, so duties, taxes or fees may be payable on delivery.
Cover for defects is set out on the warranty page.
Frequently Asked Questions
Is US to UK ring size conversion different for men and women?
No. The same chart applies to everyone: a US 7 is a UK O and a US 10 is a UK U regardless of who wears the ring. Ring sizes measure the finger, not the person, so there is no separate men's or women's conversion to worry about.
What is a US size 8 ring in UK sizes?
A US 8 is a UK Q in our size menu. If you have been measured as a US 7.5, that pairs with P; a US 8.5 pairs with R. If you fall between two, test both on a sizer rather than rounding.
What is a UK size S in US ring sizes?
A UK S is a US 9 in our size menu. The neighbouring sizes are R at US 8.5 and T at US 9.5. Choose S in the size menu at checkout and the ring you receive is the one the chart describes.
Why does your US to UK ring size chart differ from other charts?
Because our pairs come from fitting our own comfort-fit bands rather than from a generic table. Standard charts line the UK and US columns up slightly differently, and you can see that on our Ring Size Chart page. For ordering from us, use the pairs in our size menu.
Do I need a bigger size for an 8mm band than a 4mm band?
Not automatically, but an 8mm band feels snugger than a 4mm band in the same size because it covers more of the finger. Rather than sizing up on a guess, measure with the metal sizer that matches the width you intend to buy and wear it for a few hours.
Can my partner and I order a matching set in two different sizes?
Yes. Our Ring 1 / Ring 2 sets come in fixed width pairings such as 4mm and 6mm, and each ring is sized separately. One of you can order in UK letters and the other in US numbers, converting from the same chart, and the set arrives as a pair.
How long do I have to exchange a ring that is the wrong size?
You have 90 days under our size exchange, with the details set out in our Refunds and Returns policy.
Conclusion
Find your US or UK size in the chart, read across, and choose that pair in the size menu on the product page. If you're between sizes or moving to a wider band, order the free ring sizer or a metal sizer in your intended width before you commit. And if the fit still isn't right when the ring arrives, the 90-day size exchange is there to put it right.