Updated October 22, 2026 · By Enzo, founder of Laveran Paris
Key takeaways
- In France, ring size = finger circumference in millimeters: a 54 mm finger circumference is a size 54 (inside diameter 17.2 mm).
- Most searched conversions: 52 = US 6, 54 = US 6.75 to 7, 57 = US 8, 62 = US 10.
- Most common sizes: 50 to 54 for women, 58 to 62 for men.
- At Laveran, resizing is free for life and the ring sizer is free: a wrong size is never final.
In France, a ring size is the finger circumference measured in millimeters: a 54 mm finger circumference gives a size 54, which is a 17.2 mm inside diameter and a US size 6.75 to 7. Women most often wear sizes 50 to 54, men 58 to 62. This guide puts every conversion in a single chart (France, US, UK, Italy, Switzerland, Japan, diameter in mm), shows how to measure your ring size at home in two minutes, and explains what to do if you get it wrong.
Contents
- What is my ring size? The complete conversion chart
- How do you measure your ring size at home?
- Ring size in mm and cm: how do you read your measurement?
- How do you convert a US ring size to a French size?
- UK, Italian, Swiss and Japanese sizes: how do you convert them?
- What is the average ring size for women and men?
- How do you find her ring size without her knowing?
- What if the size is wrong?
- How much does a Laveran ring cost once you know the size?
- Frequently asked questions
What is my ring size? The complete conversion chart
Find your finger circumference (or the inside diameter of a ring that fits you) in the left-hand columns: the row gives your size in every country. The French size is the simplest reference, because it reads directly in millimeters.
| French size (finger circumference) | Inside diameter | US / Canada | UK / Australia | Italy / Spain / Switzerland | Japan |
|---|---|---|---|---|---|
| 44 | 14.0 mm | 3 | F | 4 | 4 |
| 45 | 14.3 mm | 3.25 | G | 5 | 5 |
| 46 | 14.6 mm | 3.75 | G½ | 6 | 6 |
| 47 | 15.0 mm | 4 | H½ | 7 | 7 |
| 48 | 15.3 mm | 4.5 | I | 8 | 8 |
| 49 | 15.6 mm | 5 | J | 9 | 9 |
| 50 | 15.9 mm | 5.25 | K | 10 | 10 |
| 51 | 16.2 mm | 5.75 | K½ | 11 | 11 |
| 52 | 16.6 mm | 6 | L½ | 12 | 12 |
| 53 | 16.9 mm | 6.5 | M | 13 | 13 |
| 54 | 17.2 mm | 6.75 | N | 14 | 14 |
| 55 | 17.5 mm | 7.25 | O | 15 | 15 |
| 56 | 17.8 mm | 7.5 | O½ | 16 | 16 |
| 57 | 18.1 mm | 8 | P½ | 17 | 17 |
| 58 | 18.5 mm | 8.5 | Q | 18 | 18 |
| 59 | 18.8 mm | 8.75 | R | 19 | 19 |
| 60 | 19.1 mm | 9.25 | S | 20 | 20 |
| 61 | 19.4 mm | 9.5 | S½ | 21 | 21 |
| 62 | 19.7 mm | 10 | T½ | 22 | 22 |
| 63 | 20.1 mm | 10.25 | U | 23 | 23 |
| 64 | 20.4 mm | 10.75 | V | 24 | 24 |
| 65 | 20.7 mm | 11.25 | W | 25 | 25 |
| 66 | 21.0 mm | 11.5 | W½ | 26 | 26 |
| 67 | 21.3 mm | 12 | X½ | 27 | 27 |
| 68 | 21.6 mm | 12.25 | Y | 28 | 28 |
| 69 | 22.0 mm | 12.75 | Z | 29 | 29 |
| 70 | 22.3 mm | 13 | Z+1 | 30 | 30 |
Foreign sizes are rounded to the nearest quarter size (US) or half letter (UK); from one brand to another, the difference can reach a quarter size. When in doubt, the measurement in millimeters always prevails. For sizes outside the chart, add about 1 mm of finger circumference per French size.
How do you measure your ring size at home?
Two reliable methods: measure the inside diameter of a ring that fits you, or measure your finger with a strip of paper.
Method 1: with a ring you already wear
- Choose a ring that fits you perfectly, worn on the same finger.
- Lay it flat on a ruler and measure the inside diameter, from one inner edge to the other, without the metal.
- Find that diameter in the chart: 16.6 mm is a size 52, 17.2 mm a size 54.
Method 2: with a strip of paper or a string
- Wrap a thin strip of paper or a non-stretch string around the base of your finger, without tightening.
- Mark with a pen the point where the paper overlaps.
- Unroll it and measure the length in millimeters: that is your French size (52 mm = size 52).
For an even more reliable result, use a ring sizer: request our free ring sizer, or have your size taken in a showroom. Every method in detail: how to measure your ring size.
Four tips to get it right
- Measure at the end of the day, at normal temperature: fingers are thinner in the morning and in the cold.
- Mind the knuckle: the ring has to slide over it. If your knuckle is prominent, aim between the base measurement and the knuckle measurement.
- Wide band, size up: above 5 to 6 mm wide, go up half a size to one size.
- Between two sizes, take the larger one: a slightly loose ring can be worn, a ring that is too tight cannot.
Not sure about your size? In our 11 showrooms, by appointment, an expert measures your finger with a professional ring sizer in two minutes; by video call, we guide you step by step. The ring sizer is free, and resizing is free for life. Book an appointment → · Request the ring sizer on WhatsApp →
Ring size in mm and cm: how do you read your measurement?
If you measured a finger circumference, the size is the number of millimeters; if you measured the diameter of a ring, multiply it by 3.14. A few of the most searched examples:
- Size 50: 50 mm finger circumference, 15.9 mm diameter.
- Size 52: 52 mm finger circumference, 16.6 mm diameter.
- Size 54: 54 mm finger circumference, 17.2 mm diameter.
- Size 56: 56 mm finger circumference, 17.8 mm diameter.
- Size 58: 58 mm finger circumference, 18.5 mm diameter.
- Size 60: 60 mm finger circumference, 19.1 mm diameter.
In centimeters, just move the decimal point: a 5.4 cm finger circumference gives a size 54, 6 cm a size 60 and 7 cm a size 70, a large size mostly worn by men. Be careful not to mix them up: a 17 mm (1.7 cm) diameter is a size 53, not a size 17.
How do you convert a US ring size to a French size?
Each US size matches a precise finger circumference: US 6 is 51.9 mm (size 52 in France), US 7 is 54.4 mm (54 or 55) and US 8 is 57 mm (57). From one US size to the next, the circumference grows by about 2.5 mm, that is two to three French sizes. American brands and many international websites use this system.
| US size | Finger circumference | Inside diameter | French size |
|---|---|---|---|
| 4 | 46.8 mm | 14.9 mm | 47 |
| 4.5 | 48.0 mm | 15.3 mm | 48 |
| 5 | 49.3 mm | 15.7 mm | 49 or 50 |
| 5.5 | 50.6 mm | 16.1 mm | 50 or 51 |
| 6 | 51.9 mm | 16.5 mm | 52 |
| 6.5 | 53.1 mm | 16.9 mm | 53 |
| 7 | 54.4 mm | 17.3 mm | 54 or 55 |
| 7.5 | 55.7 mm | 17.7 mm | 55 or 56 |
| 8 | 57.0 mm | 18.1 mm | 57 |
| 8.5 | 58.2 mm | 18.5 mm | 58 |
| 9 | 59.5 mm | 18.9 mm | 59 or 60 |
| 9.5 | 60.8 mm | 19.4 mm | 61 |
| 10 | 62.1 mm | 19.8 mm | 62 |
| 10.5 | 63.4 mm | 20.2 mm | 63 or 64 |
| 11 | 64.6 mm | 20.6 mm | 64 or 65 |
| 11.5 | 65.9 mm | 21.0 mm | 66 |
| 12 | 67.2 mm | 21.4 mm | 67 |
| 12.5 | 68.5 mm | 21.8 mm | 68 or 69 |
| 13 | 69.7 mm | 22.2 mm | 70 |
To go from a French size to a US size, use the complete chart: 52 = US 6, 54 = US 6.75, 57 = US 8, 60 = US 9.25, 62 = US 10.
UK, Italian, Swiss and Japanese sizes: how do you convert them?
In the United Kingdom, ring sizes are letters; in Italy, Spain and Switzerland, the size is the French size minus 40; in Japan, the size is very close to the same calculation.
- UK and Australia: from A to Z, with half letters. French size 52 is L½, 54 is N, 57 is P½ and 62 is T½.
- Italy, Spain, Switzerland: a French size 54 is a size 14, a 60 is a 20.
- Japan: a Japanese size 13 is about a size 53, a size 17 about a size 57.
- Germany, Belgium: as in France, the size is usually the finger circumference in millimeters.
What is the average ring size for women and men?
Most women wear a ring size between 50 and 54, and most men between 58 and 62. These are guidelines, not rules: your build, the chosen finger and the season all change the size.
- Women's ring size: most often 52 or 53 (US 6 to 6.5). Slim fingers: 48 to 50; wider fingers: 55 to 57.
- Men's ring size: around 60 (US 9 to 9.25). Wide fingers: up to 66 or 68.
- By finger: the middle finger is usually half a size to one size larger than the ring finger, and the dominant hand slightly larger.
For a wedding band or a signet ring, see also our guide to men's ring sizes.
How do you find her ring size without her knowing?
The most reliable way is to discreetly borrow a ring she wears on her ring finger and measure its inside diameter, or trace its inside on a sheet of paper. Other options:
- ask someone close to her who can keep a secret;
- start from a ring she wears on her middle finger, then go down about half a size;
- as a last resort, choose an average size (52 or 53): at Laveran, resizing is free for life, even after the proposal.
Planning a proposal over the holidays? Also read when to order the ring for a Christmas proposal: for Christmas, order before the end of November.
What if the size is wrong?
At Laveran, it is never a problem: resizing is free, for life. A ring that is too big or too small is adjusted by our workshop, even years after purchase.
- Free resizing for life.
- Returns within 30 days.
- Lifetime warranty, free polishing and prong check for life.
- Free, insured delivery, handed over in person.
If your current ring spins or slips, our tips to adjust it: ring too big, what to do?
How much does a Laveran ring cost once you know the size?
A lab-grown diamond engagement ring starts at €880 at Laveran, a diamond wedding band at €704 and a men's band at €90 in 925 silver. Every ring is made to order, in your size, in 2 to 3 weeks; some models are available in stock. Prices as of October 22, 2026:
| Model | Type | Starting price |
|---|---|---|
| Montaigne 6-prong ring | Solitaire, 0.30-carat H/VS2 diamond | €880 |
| Montaigne 6-prong ring | Solitaire, 1-carat H/VS2 diamond | €1,744 |
| Vendôme ring | Solitaire on a pavé band | €1,280 |
| Odéon ring | Solitaire with a diamond halo | €1,480 |
| Concorde round diamond band | Diamond wedding band, 0.50 carat total | €704 |
| Jonc Parisien men's band | Men's band, 2 mm | €90 (925 silver), €400 (18-carat gold or platinum) |
Platinum costs the same as 18-carat gold. Diamonds are IGI or GIA certified and non-fluorescent, up to 80% less expensive than a natural diamond. Engraving is free and installment payment is available with Alma. All collections: engagement rings, diamond wedding bands, men's wedding bands.
Frequently asked questions
What ring size is 54 mm?
A 54 mm finger circumference is a size 54 in France, which is a 17.2 mm inside diameter, a US size 6.75 to 7, a size N in the UK and a size 14 in Italy or Switzerland.
What is a size 52 in mm?
A size 52 ring has a 52 mm inside circumference and a 16.6 mm inside diameter. It matches a US size 6 and a UK L½.
What ring size is a 7 cm finger circumference?
A 7 cm (70 mm) finger circumference is a size 70, which is a US size 13. It is a large size, mostly worn by men. A 6 cm finger circumference is a size 60.
What is a US size 8 in French sizes?
A US size 8 measures 57 mm in circumference: it is a size 57 in France, with an 18.1 mm inside diameter.
What does a size 7 ring correspond to?
In US sizing, a 7 measures 54.4 mm: it is a size 54 or 55 in France. In Italian or Swiss sizing, a size 7 is a French size 47.
What does "UK size 12" mean for a ring?
British ring sizes are letters (from A to Z), not numbers. A "UK 12" is usually a clothing size. For a ring, look for the letter: for example, N is a French size 54.
Should I size up?
If you hesitate between two sizes, yes, take the larger one. Do the same for a wide band, above 5 to 6 mm, which feels tighter than a thin one.
What if my Laveran ring is not the right size?
Nothing serious: resizing is free for life, and you can return the ring within 30 days. The ring sizer is free if you want to check your size before ordering.
Found your size? All that is left is choosing the ring. Book an appointment in one of our 11 showrooms or by video call: an expert confirms your size with a ring sizer and shows you the models on your finger.
Book an appointment → · See engagement rings →
