Free Ring Size Converter (+ Guide)

What is a ring size converter?

A ring size converter changes a ring size from one country's system to another's. It turns your size into the length around the inside of the ring, then into each other system.

How to use the ring size converter

You need a size you know and the system it's in.

US sizes take quarters and halves, like 6.25 or 6.5.

A worked example

Here's the example the calculator loads when you press Try an example: a US size 7.

A US 7 is 2.55 × 7 + 36.5 = 54.35 mm around. That's (54.35 − 40) ÷ 1.25 = 11.5 letters above C, so UK N½.

Europe rounds 54.35 mm to size 54.5, Italy's is 54 − 40 = 14, and Germany's diameter is 17.3 mm, sold as 17.5.

Which countries use which system

The systems split by region.

US, Canada and Mexico

Numbers with quarter sizes, usually from 3 to 13.

UK, Ireland, Australia and New Zealand

Letters from A to Z with half sizes, then Z+1 and up.

Most of Europe

The inside length in mm (ISO 8653). Italy, Spain and Switzerland drop the 40, and Germany and the Netherlands use the inside width in mm.

Mistakes to avoid

These are the ways a converted size lands wrong.

• Reading a US size off a UK chart, or the other way round
• Rounding down between 2 sizes instead of up
• Forgetting that wide bands fit tighter
• Trusting a brand's chart without checking it against the mm

Not sure of your size at all? The ring size calculator measures it from a paper strip.

Who is the ring size converter for?

It's for anyone buying from a shop in another country, and these tools help around it.

• Ring size calculator – for measuring your size at home
• Shoe size converter – for shoe sizes between countries
• Currency converter – for the price in your money
• Card fees abroad calculator – for what your card adds
• Time zone converter – for when the shop abroad is open

Convert through the mm, and every chart agrees.