Ring Size Calculator | US, UK, EU and JP Sizes
Convert finger circumference or ring diameter into US, UK, EU, and Japanese ring sizes for online jewelry sizing checks.
Estimated Ring Size
Find Ring Size from Circumference or Diameter
Enter finger circumference or ring inner diameter to estimate ring size across US, UK, EU, and Japanese sizing systems.
Measure at the Right Time
Finger size can change with temperature, swelling, time of day, and ring width. Measure more than once and avoid sizing when hands are very cold or hot.
When Ring Size Conversion Helps
Use it before ordering rings online, comparing international size charts, checking an existing ring, or preparing a gift when you only have a measurement.
Overview
Ring Size Calculator converts a finger circumference or diameter measurement into a ring size across UK, US, EU, and international sizing charts. It helps ensure the correct size when ordering a ring online without trying it in person.
Typical Use Cases
Use this when ordering a ring as a gift and you only have the recipient's finger measurement, when converting a ring size between different country formats, or when checking whether your own size matches an international standard.
Using the Tool
- Measure the finger circumference with a strip of paper or a ring sizer.
- Enter the measurement in millimetres.
- Click Calculate to see the equivalent size in UK, US, and EU formats.
Questions People Ask
How do I measure my ring size at home?
Wrap a thin strip of paper snugly around the base of your finger, mark where it overlaps, and measure the length in millimetres. That is the circumference.
Should I measure in the morning or evening?
Fingers swell slightly during the day and in warm weather. Measure at the end of the day for a size that accommodates normal variation.
What if I am between two ring sizes?
Choose the larger of the two sizes. A ring that is slightly loose is easier to resize or wear comfortably than one that is too tight.
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