Ring Size Calculator
Enter one measurement or known size. The calculator returns US, UK, EU, Japan, India, diameter, and circumference from the same engine used in the app.
Published by Ring Sizer · App developer: Pawel Boguta · Updated
54 mm circumference is about US 7, UK N 1/2, EU 54.
Thin band chart size, with no fit adjustment.
Converted sizes
- US / Canada
- 7
- UK / Australia
- N 1/2
- EU / ISO
- 54
- Japan
- 14
- India
- 14
- Diameter
- 17.2 mm
- Circumference (mm)
- 54.0 mm
- Circumference (in)
- 2.126 in
Uses the Ring Sizer conversion model. Measured values and nominal size conversions can round differently. Use thin band for a chart conversion. See our methodology and supported ranges.
Measured a finger
Choose circumference and enter the string or paper length.
Measured a ring
Choose diameter and enter the inside width across the center.
Know a size
Choose US, UK, EU, or India to convert it into every system.
Sources and methodology
Read our conversion rules, supported ranges, and measurement limitations.
Get your exact size, without the jeweler
The calculator is best for converting a measurement you already have. To capture that measurement in the first place, the app reads your size right on screen and adjusts for band width, the most accurate option short of a trip to the jeweler.
Download Ring Sizer- Free download · In-app purchases
- iOS
- No sign-up
- Works offline
FAQ
What measurement should I enter?
Use inner circumference if you measured with string or paper. Use inner diameter if you measured a ring that already fits.
Should I choose a wide band?
Choose wide or extra wide when the ring band is thicker than about 6 mm. Wider bands feel tighter, so the calculator recommends a slightly larger fit.
Is this accurate enough to order a ring?
It is accurate enough for a strong home estimate when the measurement is careful. Confirm expensive or borderline sizes with a jeweler.