Ring Size Calculator
Convert between any ring size system instantly. Select your known size and see accurate conversions across US, UK, EU, Japan, Switzerland, diameter, and circumference.
Select a size above to see instant conversions across all systems
Frequently Asked Questions
How accurate is this ring size calculator?
Our calculator uses industry-standard conversion data used by jewelers worldwide. It provides accurate conversions between all major ring size systems including US, UK, EU, Japan, and Switzerland, as well as diameter and circumference measurements in millimeters.
What is the most common ring size?
The most common ring size for women in the US is size 6 to 7 (EU 51.5–54, UK L–N). For men, the most common size is 9 to 10 (EU 59–61.5, UK R–T). However, ring sizes vary significantly between individuals.
How do I measure my ring size at home?
You can measure your ring size at home using a piece of string or paper strip. Wrap it around your finger, mark where it overlaps, then measure the length in millimeters. Use our calculator to convert that circumference measurement to any ring size system.
Do ring sizes differ between countries?
Yes, different countries use different ring size systems. The US and Canada use numerical sizes (3–15), the UK and Australia use letter-based sizes (A–Z), and Europe uses circumference-based numbers (44–74). Our calculator converts between all these systems instantly.
Should I size up or down if I'm between sizes?
If you're between sizes, it's generally recommended to size up rather than down. A ring that's slightly loose is more comfortable and easier to remove than one that's too tight. Factors like temperature, humidity, and time of day can also affect finger size.
Can I convert diameter to ring size?
Yes! Simply select 'Diameter (mm)' as your input system in our calculator, enter the diameter of your ring or finger, and we'll instantly show you the equivalent size in US, UK, EU, Japan, Switzerland, and circumference.
How to Use the Ring Size Calculator
Our free ring size calculator makes it easy to find your perfect fit across any sizing system used worldwide. Whether you know your US size and need the European equivalent, or you've measured your finger diameter and want to know your UK letter size, this tool handles it all instantly.
Step-by-Step Instructions
- Choose your sizing system — Select the system you already know (US, UK, EU, Japan, Switzerland, diameter, or circumference).
- Enter or select your size — Type a value or click one of the preset chips for instant results.
- View all conversions— See your size in every other system, plus a visual reference showing the ring's approximate inner diameter.
Tips for Accurate Measurement
- Measure at the end of the day when fingers are at their largest.
- Measure the specific finger you plan to wear the ring on — each finger is different.
- Take multiple measurements on different days for the best accuracy.
- If your knuckle is significantly larger than your finger base, measure both and choose a size in between.