Find your ring size
What does US 4 mean?
US identifies the American sizing scale; 4 is the size number, not a measurement in millimetres. US 4 is approximately 14.9 mm across the inside of the ring and 46.8 mm around the inside. A higher US number means a larger ring. The same scale applies to all genders.
A ring size is separate from a diamond’s carat weight (ct) and gold purity (10k, 14k or 18k). European systems differ: French/EU sizes commonly refer approximately to inner circumference in millimetres, while some systems use inner diameter. Always compare the measurements, not just the size number.
US sizes and measurements
| US | Inside diameter (mm) | Inside circumference (mm) |
|---|
| US 4 | 14.9 | 46.8 |
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| US 4.5 | 15.3 | 48.0 |
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| US 5 | 15.7 | 49.3 |
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| US 5.5 | 16.1 | 50.6 |
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| US 6 | 16.5 | 51.9 |
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| US 6.5 | 16.9 | 53.1 |
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| US 7 | 17.3 | 54.4 |
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| US 7.5 | 17.7 | 55.7 |
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| US 8 | 18.1 | 57.0 |
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| US 8.5 | 18.5 | 58.3 |
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| US 9 | 18.9 | 59.5 |
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| US 9.5 | 19.4 | 60.8 |
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| US 10 | 19.8 | 62.1 |
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| US 10.5 | 20.2 | 63.4 |
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| US 11 | 20.6 | 64.6 |
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| US 11.5 | 21.0 | 65.9 |
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| US 12 | 21.4 | 67.2 |
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Measurements are approximate and rounded; conversion charts can vary slightly. For example, US 7 is about 17.3 mm in diameter and 54.4 mm in circumference — close to an EU circumference size of 54. The illustrations are explanatory, not a screen-sized measuring tool.
Method 1 · Measure a ring that fits
Inside diameter, measured across the centre
- Choose a round ring that fits the same finger on the same hand comfortably. A ring worn on another finger may give the wrong result.
- Lay it flat and measure straight across the centre from one inside edge to the opposite inside edge, using a ruler with millimetres or callipers. Exclude the metal band.
- Match this inside diameter to the table. For example, an inside diameter of about 18.1 mm corresponds to US 8.
Method 2 · Measure your finger
- Use a narrow strip of paper or a flexible, non-stretch measuring tape. Wrap it around the base of the intended finger; it should touch the skin without squeezing.
- Mark where the ends meet, lay the strip flat and measure to the mark in millimetres. This is circumference, not diameter; use the circumference column directly.
- Check that the loop can pass over the knuckle with gentle resistance. Repeat the measurement a few times; if the knuckle is much wider than the finger base, have a jeweller check the fit.
For a comfortable fit
- Measure near the end of the day at a comfortable room temperature. Cold fingers, heat, exercise or swelling can change the result. Measure the correct hand.
- If you fall between two sizes, try the larger half size. A wide band or several stacked rings can feel tighter; confirm the fit with a sizer of similar width rather than automatically adding a full size.
- A good fit stays in place but passes over the knuckle without force. For the most reliable result, ask a jeweller to measure you with a ring sizer, especially for wide or full-eternity bands.
Still unsure? Contact LENELIS before ordering. Share your measurement in millimetres and whether it is diameter or circumference.
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