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Ring Size Calculator – Find Your Ring Size in US, UK & EU Sizes

Find the perfect ring fit with our Ring Size Calculator. Measure your finger circumference or diameter to get your ring size in US, UK, EU, Japan, and India standards — essential before buying rings online or as a gift.

How to Measure:

  1. Wrap string/paper around finger base
  2. Mark where it overlaps
  3. Measure length in mm
  4. Measure at end of day (fingers swell)

Ring Size Results

Enter your measurement and click Calculate to see ring sizes

Ring Size Chart

USUKEUDiameterCircumference
3F4414.1 mm44.2 mm
3.5G4514.5 mm45.5 mm
4H4714.9 mm46.8 mm
4.5I4815.3 mm48 mm
5J4915.7 mm49.3 mm
5.5K5016.1 mm50.6 mm
6L5216.5 mm51.9 mm
6.5M5316.9 mm53.1 mm
7N5417.3 mm54.4 mm
7.5O5617.7 mm55.7 mm
8P5718.1 mm57 mm
8.5Q5818.5 mm58.3 mm
9R5919 mm59.5 mm
9.5S6119.4 mm60.8 mm
10T6219.8 mm62.1 mm
10.5U6320.2 mm63.4 mm
11V6520.6 mm64.6 mm
11.5W6621 mm65.9 mm
12X6721.4 mm67.2 mm
12.5Y6821.8 mm68.5 mm
13Z7022.2 mm69.7 mm

How to Use This Ring Size Calculator

1

Measure your finger

Wrap a strip of paper or string around the base of your finger. Mark where it overlaps, then measure the length in millimeters.

2

Select measurement type

Choose whether you measured circumference (around the finger) or diameter (across an existing ring that fits).

3

Enter your measurement

Input the measurement in millimeters or inches. The calculator shows your size in US, UK, EU, Japan, and India standards.

Ring Size Conversion Tips

Measure at the Right Time

Fingers swell throughout the day. Measure at the end of the day when fingers are largest. Avoid measuring when your hands are cold — fingers shrink in cold weather.

Consider the Ring Width

Wider bands feel tighter. If buying a ring wider than 6mm, consider going up half a size. A 4mm band and 10mm band in the same size will fit differently.

Dominant Hand Factor

Your dominant hand is typically half a size larger. If measuring for your right hand and you're right-handed, expect a slightly larger size than your left hand.

Knuckle Considerations

If your knuckle is significantly larger than your finger base, measure both and choose a size in between. The ring must fit over the knuckle but not spin loosely.

International Ring Size Standards

RegionSystemExample SizeNotes
United StatesNumerical5, 5.5, 6, 6.5...Half sizes common
United KingdomAlphabeticalJ, K, L, M...Letters A-Z
EuropeCircumference (mm)48, 49, 50...Inner circumference
JapanNumerical8, 9, 10...Different scale than US
IndiaNumerical10, 11, 12...Similar to US but varies

Frequently Asked Questions

What if I'm between sizes?
Size up rather than down. It's easier to add sizing beads or have a ring resized smaller than to add material. A slightly loose ring is more comfortable than one that's too tight.
How accurate is this calculator?
The calculator is as accurate as your measurement. Paper strip measurements are typically within half a size. For expensive rings, visit a jeweler for professional sizing.
Do ring sizes change over time?
Yes. Weight changes, pregnancy, arthritis, and aging can all affect finger size. Re-measure before buying important rings if it's been more than a year since your last sizing.
Can I use an existing ring to find my size?
Yes. Measure the inside diameter of a ring that fits the intended finger well. Use the diameter measurement option in this calculator for the most accurate result.
Why do different jewelers give different sizes?
Ring sizing isn't perfectly standardized. Some jewelers use slightly different mandrels or measurement methods. Always ask which sizing system they use and get sized by the same jeweler who'll make your ring.

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