| US / Canada | UK / Australia | Europe (ISO) | Japan | Inner Diameter | Circumference |
|---|---|---|---|---|---|
| 4 | H | 46.8 | 7 | 14.88 mm (0.586") | 46.8 mm |
| 5 | J 1/2 | 49.3 | 9 | 15.70 mm (0.618") | 49.3 mm |
| 6 | L 1/2 | 51.9 | 11 | 16.51 mm (0.650") | 51.9 mm |
| 7 | N 1/2 | 54.4 | 14 | 17.32 mm (0.682") | 54.4 mm |
| 8 | P 1/2 | 57.0 | 16 | 18.14 mm (0.714") | 57.0 mm |
| 9 | R 1/2 | 59.5 | 19 | 18.95 mm (0.746") | 59.5 mm |
| 10 | T 1/2 | 62.1 | 21 | 19.76 mm (0.778") | 62.1 mm |
| 11 | V 1/2 | 64.6 | 23 | 20.57 mm (0.810") | 64.6 mm |
| 12 | X 1/2 | 67.2 | 25 | 21.39 mm (0.842") | 67.2 mm |
Find your exact ring size from home with complete confidence using our free online ring sizer. By synchronizing digital pixels directly with real-world millimeter dimensions, this interactive circular ring sizer delivers authentic 1:1 scale verification directly on your smartphone, tablet, or computer monitor. Place an existing ring flat on the screen to instantly determine your international size across US & Canada, United Kingdom & Australia, Europe (ISO), and Japan without waiting for physical plastic ring gauges or making unnecessary trips to jewelry stores.
Determining ring size on screen takes less than 30 seconds using our simple 3-step physical verification method:
Jewelers around the world use different sizing scales. True Scale Ring Sizer performs real-time simultaneous conversion across all major international jewelry standards:
Follow these jeweler-approved recommendations to guarantee a comfortable, lasting fit:
Everything you need to know about measuring rings and international sizing.
First, calibrate your screen with a standard credit card (or enter your screen diagonal) to ensure 100% 1:1 physical accuracy. Next, place an existing ring that fits your finger flat on the screen over the circular template. Adjust the on-screen slider until the outer boundary of the white circle template matches the inside edge of your ring perfectly. Your exact US, UK, EU, and Japanese ring size will display immediately.
Always align the circle template with the inner edge (inside diameter) of the physical ring, NOT the outside edge. Ring band thickness varies widely between jewelers, but inner diameter strictly dictates finger fit.
US and Canadian ring sizes use numeric increments (e.g. 7). UK and Australian sizes use letters (e.g. US 7 is N 1/2). European sizes use ISO standard inner circumference in millimeters (e.g. 54.4 mm for US 7), and Japanese sizes use a continuous numeric scale (e.g. 14 for US 7). Our tool displays all four international systems simultaneously.
If your ring falls between two sizes, we generally recommend sizing up to the larger half or quarter size, particularly if the ring band is wide (wider than 4 mm) or if you are measuring during colder weather when fingers naturally shrink slightly.
Yes! Modern smartphone glass (such as Gorilla Glass or Ceramic Shield) has a Mohs hardness of 6+, making it highly resistant to scratches from standard jewelry metals (gold, silver, platinum, titanium). You can tap the Lock button to freeze the screen so the ring contact does not move the slider.
Standard digital screens have different pixel densities. A circle drawn with 60 pixels might be 15 mm on a phone but 19 mm on a desktop monitor. Calibrating with an ISO credit card ensures the circle rendered on your glass matches true physical millimeters exactly.