Ring Size Converter
Enter a ring size in any system and instantly see the equivalent in all others. Buying from an overseas jeweller or measuring at home? Type your finger circumference in mm and find your size. Nothing uploaded.
How to measure your ring size at home
- Cut a thin strip of paper about 15 cm long.
- Wrap it snugly around the base of the finger you want to size. Do not wrap it too tight - you need to be able to slide a ring over your knuckle.
- Use a pen to mark where the paper overlaps.
- Lay the paper flat and measure the distance from the end to your mark with a ruler. That is your circumference in mm.
- Enter the measurement below.
All size systems
Full ring size reference chart
| US | UK | EU | JP | Circumference (mm) | Diameter (mm) |
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Learn more: Ring sizing systems and measurement
Why ring size systems differ between countries
Ring size systems were developed independently in different countries before international standards existed. The US uses a numeric scale from about 3 to 13. The UK uses letters from D to Z+4. Europe uses a number that equals the inner circumference of the ring in millimetres. Japan uses its own integer scale. There is no simple conversion formula - you need a lookup table, which is exactly what this converter uses.
How to measure your ring size at home
Cut a strip of paper about 15 cm long and 5 mm wide. Wrap it around your finger at the base - snug but not tight, as you need to be able to slide a ring over your knuckle. Mark where it meets with a pen, then lay the paper flat and measure from the end to your mark with a ruler. That measurement in mm is your finger circumference.
FAQ
What is a US size 7 ring in EU?
US ring size 7 is EU size 54. It has an inner circumference of approximately 54.4 mm and an inner diameter of 17.3 mm. UK equivalent is size N.
How do I measure my ring size at home in mm?
Wrap a thin strip of paper snugly around the base of your finger. Mark where the paper overlaps, then lay it flat and measure from the end to the mark with a ruler. This gives your circumference in mm. Enter that number into the converter to find your size in all systems.
Why are ring sizes different in different countries?
Different countries adopted different measurement conventions. The US system uses arbitrary numbers (3-13); UK sizes use letters; EU sizes are the inner circumference in millimetres; Japanese sizes are their own integer scale. The inner circumference in mm is the universal measurement that all systems derive from.