Ring size help for US buyers
US ring size to European size: conversion chart in mm and inches
Know her US size? Tap it below and you have the European size we make to, in a second. Don't know it? There is a discreet way to find out.
Updated 10 November 2026. By Alexey Kovernikov, owner of Kove Jewelry in Prague: a page from a shop that makes rings to EU sizes, not a neutral review.
US 6¾ is
EU 54
54 mm around the inside · 17.2 mm across
Tap her US size
Between two sizes, or a band wider than about 6 mm? Go one EU size up. Not sure at all? Send us a photo of a ring she wears, lying on a ruler, and we tell you the size.
American jewelers size rings on the US scale (6, 6½, 7). European shops, including ours, use the EU or ISO scale, where the number is the inside circumference of the ring in millimeters: an EU 54 measures 54 mm around the inside. If you know her US size, or can find it out, the chart below gives the EU size to order, with the inside diameter and circumference in millimeters and inches so you can check it against a ring she already owns.
US to EU ring size chart
Find her US size in the first column. The EU size is what you choose when you order; the ring is made to that inside circumference. The diameter is the distance across the inside of the ring, which is what you can measure with a ruler on a ring she owns.
| US size | EU size | Inside diameter | Inside circumference |
|---|---|---|---|
| US 3 | EU 44 | 14.0 mm / 0.55 in | 44 mm / 1.73 in |
| US 3¼ | EU 45 | 14.3 mm / 0.56 in | 45 mm / 1.77 in |
| US 3¾ | EU 46 | 14.6 mm / 0.58 in | 46 mm / 1.81 in |
| US 4 | EU 47 | 15.0 mm / 0.59 in | 47 mm / 1.85 in |
| US 4½ | EU 48 | 15.3 mm / 0.60 in | 48 mm / 1.89 in |
| US 4¾ | EU 49 | 15.6 mm / 0.61 in | 49 mm / 1.93 in |
| US 5¼ | EU 50 | 15.9 mm / 0.63 in | 50 mm / 1.97 in |
| US 5½ | EU 51 | 16.2 mm / 0.64 in | 51 mm / 2.01 in |
| US 6 | EU 52 | 16.6 mm / 0.65 in | 52 mm / 2.05 in |
| US 6¼ | EU 53 | 16.9 mm / 0.66 in | 53 mm / 2.09 in |
| US 6¾ | EU 54 | 17.2 mm / 0.68 in | 54 mm / 2.13 in |
| US 7 | EU 55 | 17.5 mm / 0.69 in | 55 mm / 2.17 in |
| US 7½ | EU 56 | 17.8 mm / 0.70 in | 56 mm / 2.20 in |
| US 8 | EU 57 | 18.1 mm / 0.71 in | 57 mm / 2.24 in |
| US 8¼ | EU 58 | 18.5 mm / 0.73 in | 58 mm / 2.28 in |
| US 8¾ | EU 59 | 18.8 mm / 0.74 in | 59 mm / 2.32 in |
| US 9 | EU 60 | 19.1 mm / 0.75 in | 60 mm / 2.36 in |
| US 9½ | EU 61 | 19.4 mm / 0.76 in | 61 mm / 2.40 in |
| US 10 | EU 62 | 19.7 mm / 0.78 in | 62 mm / 2.44 in |
| US 10¼ | EU 63 | 20.1 mm / 0.79 in | 63 mm / 2.48 in |
| US 10¾ | EU 64 | 20.4 mm / 0.80 in | 64 mm / 2.52 in |
| US 11 | EU 65 | 20.7 mm / 0.81 in | 65 mm / 2.56 in |
| US 11½ | EU 66 | 21.0 mm / 0.83 in | 66 mm / 2.60 in |
Quarter sizes are rounded. European sizes move in whole millimeters of circumference, US sizes in quarter steps of roughly 0.6 mm, so the two scales never line up exactly and every published chart rounds somewhere. If her US size is not in the first column (for example US 5 or US 6½), it sits between two rows: take the larger EU size, or write to us with the US number and we tell you which EU size we would make.
Larger than US 11½? This chart ends where our shared size data ends. For US 12, 13 or larger, write to us with the US size and we confirm the EU size and whether the design you like can be made in it.
Full method. Measuring a finger with a thread, the EU, US, UK and Russian chart side by side, and diagrams: How to measure ring size.
How to read a US size from a ring she already owns
Most American women do not know their ring size, and few rings have it stamped inside. A ring she wears on the right finger answers the question better than a guess.
- Pick a ring she wears on the finger the engagement ring will go on. In the US that is usually the left ring finger. A ring from her right hand or another finger gives a different size: fingers on the dominant hand are often slightly larger.
- Lay the ring flat on a ruler with a millimeter edge (most US rulers have one on the other side). Measure the hole, not the metal: from inner edge to inner edge, straight through the center, where it is widest.
- Find that number in the "Inside diameter" column. 16.6 mm is EU 52 (US 6), 17.2 mm is EU 54 (US 6¾), 17.5 mm is EU 55 (US 7).
- Only have an inch ruler? Inches work too, but a sixteenth of an inch is 1.6 mm, more than one EU size, so use the millimeter edge whenever you can.
Already know her US size from a jeweler, or from a ring she bought in a US store? Use that number in the chart. A size taken on a jeweler’s ring sizer is more reliable than a measurement at home.
The discreet method: two minutes while she is out
Photograph it on a ruler. Put her ring flat on a ruler, take one photo from directly above, and put the ring back. Send the photo to us on WhatsApp or by e-mail and we read the size for you.
Trace it. No ruler at hand? Lay the ring on paper and trace the inside circle with a sharp pencil. Measure across the middle of the circle later.
Ask the person who would know. Her sister, mother or a close friend may know her size, or can find it out while trying on rings together.
Nothing to go on at all? The most common women’s sizes are EU 52 to 54, which is US 6 to 6¾. Slim fingers lean towards EU 50 (US 5¼), fuller hands towards EU 56 (US 7½). Choose the likely size and use the free resize after the proposal (see below). More discreet methods: Secretly: measure a ring she already wears.
The mistakes that cost a size
A wide band runs tight. A band wider than about 6 mm (roughly a quarter inch) covers more of the finger and feels a size smaller. If the ring you are ordering is wide, go up half a US size, which means one EU size.
The knuckle. The ring has to pass over the knuckle, not just sit at the base. If her knuckle is clearly thicker than the base of the finger, a ring that fits the base will not go on. Choose a size between the two.
Cold fingers, hot fingers. Fingers shrink in the cold and right after washing, and swell in heat, after exercise or after a flight, by up to half a size. A size taken in winter in a cold room reads small. Measure at room temperature, ideally in the evening.
Guessing between sizes. Between two sizes, go up. A ring that is slightly loose can be worn and resized; a ring that will not go over the knuckle cannot be worn at all.
Diameter and circumference mixed up. A ruler across a ring gives the diameter (17.2 mm). A thread around a finger gives the circumference (54 mm). Both describe EU 54, so check which column you are reading.
If the size is wrong: the resize, honestly
Every ring is made to order to the EU size you choose, so get the size as close as you can before ordering. If it is still not right, we resize the ring once, free of charge, if you write to us within 60 days of delivery. On most designs that covers up to 2 EU sizes larger or smaller; rings with stones all the way around the band cannot be resized, and sizing down is limited on pavé designs. Write to us before sending anything and we confirm what your design allows.
What is free is the work. Shipping is a different matter for a US address: the free insured return shipping on a resize applies inside the EU only. From the US, shipping the ring to us and back, and any import charges on the way back, are yours to pay. We tell you the amount before you send the ring, so ask us first. Full terms: Return policy.
Ordering to the US? Write to us before you pay: we confirm in writing the full delivered price to your address, including US import duty, for your exact ring. How US delivery and duty work: Engagement ring from Europe shipped to the US.
Frequently asked questions
What is a US size 6 in European size?
US 6 is EU 52: an inside circumference of 52 mm (2.05 in) and an inside diameter of 16.6 mm (0.65 in). It is one of the most common women’s sizes.
What is a US size 7 in European size?
In our chart US 7 is EU 55: 55 mm (2.17 in) around the inside and 17.5 mm (0.69 in) across. A US 7 sits close to the line between EU 54 and EU 55, so if you are unsure, send us a photo of a ring she wears on a ruler and we confirm which one to make.
What is a US size 8 in European size?
US 8 is EU 57: 57 mm (2.24 in) around the inside and 18.1 mm (0.71 in) across.
What does EU 54 mean in US sizes?
EU 54 is about US 6¾: the ring measures 54 mm (2.13 in) around the inside and 17.2 mm (0.68 in) across. The EU number is simply the inside circumference in millimeters.
My girlfriend is between two US sizes. Which EU size should I order?
The larger one. Go up one more EU size if the band is wider than about 6 mm. A slightly loose ring can be worn and resized; one that will not pass the knuckle cannot be worn.
How do I find her US ring size without her knowing?
Borrow a ring she wears on the same finger, lay it on a ruler and measure the inside diameter in millimeters, then find that number in the chart. Or photograph the ring flat on a ruler from directly above and send the photo to us; we tell you the size.
Can you resize the ring if I order the wrong size from the US?
Yes: the first resize is free within 60 days of delivery, up to 2 EU sizes on most designs. The work is free, but from the US the shipping both ways and any import charges are yours; we tell you the amount before you send the ring. Rings with stones all the way around the band cannot be resized.
Have the size? Choose the ring
Sources
Made to her EU size
Épure Solitaire Round
from €935
View the ring
Vivienne Solitaire Oval
from €887
View the ring
Lumière Solitaire Marquise
from €1,047
View the ringEvery ring is made to order in the EU size you choose. Prices are live from the product pages.
Still not sure? Just ask a real person.
Tell us your idea and your budget: we answer personally and spec the best certified diamond for you, with its IGI or GIA certificate. No pressure, no obligation, no checkout.