The Complete International Ring Size Guide
How international sizing scales work, knuckle swelling factors, and band width adjustments.
An engagement ring or wedding band should slide over the knuckle with slight resistance and sit comfortably without spinning.
1. Step-by-Step Guide: How to Measure Your Ring Size at Home
If you don't have a metal jeweler's mandrel, use this foolproof home measurement method:
Step 1: Wrap Non-Stretchy Paper or Floss Around the Base
Cut a strip of paper 1/2 inch wide. Wrap it snugly around the base of the specific finger you plan to wear the ring on (your left ring finger is often a half-size different from your right ring finger!).
Step 2: Check the Knuckle Clearance
If your knuckle is larger than the base of your finger, measure your knuckle as well. Your true size must be large enough to slide over the knuckle comfortably without forcing it.
Step 3: Measure in Millimeters & Select Band Width
Lay the paper strip flat against a metric ruler. Select "Circumference (mm)" in our calculator. If you are buying a wide band (6mm+), select the wide band offset (+0.5 size).
Step 4: Export Specs for Your Jeweler
Click "📝 Export Word Card (.doc)" or "🖨️ Export PDF" to send your exact international size specifications directly to your custom ring designer or jeweler.
2. Master International Ring Size Conversion Chart
| US & Canada | UK & Australia | EU & France | Japan & Asia | Diameter (mm) | Circumference (mm) |
|---|---|---|---|---|---|
| US 4 | H 1/2 | 47 | 7 | 14.9 mm | 46.8 mm |
| US 5 | J 1/2 | 49 | 9 | 15.7 mm | 49.3 mm |
| US 6 | M | 52 | 11 | 16.5 mm | 51.9 mm |
| US 7 (Most Popular Women) | O | 54 | 14 | 17.3 mm | 54.4 mm |
| US 8 | Q | 57 | 16 | 18.1 mm | 57.0 mm |
| US 9 | R 1/2 | 60 | 18 | 18.9 mm | 59.5 mm |
| US 10 (Most Popular Men) | T 1/2 | 62 | 20 | 19.8 mm | 62.1 mm |
| US 11 | V 1/2 | 65 | 23 | 20.6 mm | 64.6 mm |
| US 12 | Y | 67 | 25 | 21.4 mm | 67.2 mm |
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Frequently Asked Questions
Can all rings be resized later if I get the size slightly wrong?
Standard gold and platinum solitaire bands can easily be resized 1 to 2 sizes up or down. However, eternity bands with diamonds all the way around, tungsten carbide, and titanium rings cannot be resized, so getting your exact size right the first time is essential.
How do I secretly find my partner's ring size for a surprise proposal?
Borrow a ring they frequently wear on their ring or middle finger, trace the inner circle onto a piece of paper, and measure the diameter in millimeters. Alternatively, place the ring directly over our on-screen circle sizer or ask their best friend or mother.