Last updated: March 2026
Understanding Ring Size Charts
A ring size chart is a conversion table that maps between the different sizing systems used by jewelers around the world. The three most common systems are US (numerical), UK (alphabetical), and EU (Continental European), each with its own scale and logic.
The US system runs from size 3 to 15 in half-size increments, where each half size represents approximately 0.4mm in diameter. The UK system assigns letters from A to Z (and beyond) to specific circumference values. The EU system uses numbers that roughly correspond to the ring's inner circumference in millimeters, making it the most intuitive of the three.
Every ring size ultimately describes the same physical measurement: the inner diameter or circumference of the ring. A US 7, UK N, and EU 54.3 are all the same ring — 17.3mm in diameter, 54.4mm in circumference. The chart above converts between all these systems so you never have to guess.
How Ring Sizing Systems Compare
The US and Canadian system is the most widely used in North America. It was standardized in the early 1900s and uses a simple numerical scale. Half sizes provide reasonably fine granularity, but some people fall between half sizes and need to choose up or down.
The UK and Australian system uses the alphabet, starting at A for very small rings (about 12mm diameter) and going up to Z for larger sizes. Beyond Z, sizes are denoted as Z+1, Z+2, and so on. The letter system can be confusing for international buyers, but it's deeply embedded in British and Commonwealth jewelry traditions.
The European system is arguably the most logical: the size number approximately equals the ring's inner circumference in millimeters. An EU 54 ring has an inner circumference of roughly 54mm. Some European countries use slight variations — French and Russian sizing differs by a constant offset — but the standard Continental system shown in this chart is the most common.
Tips for Using a Ring Size Chart
Start with millimeters. If you can measure the inner diameter or circumference of a ring in millimeters, you can find your size in any system. A ruler or calipers give the most precise measurement. Place an existing ring on a ruler and read the inner diameter — then look up that measurement in the chart.
Remember that ring size is not static. Your fingers change size with temperature, time of day, hydration, exercise, and even altitude. The best practice is to measure multiple times under normal conditions and use the size that comes up most often.
When shopping internationally, always verify which sizing system a retailer uses. A “size 9” in the US system (19mm diameter) is very different from a “size 9” in the Japanese system (roughly 15.5mm diameter). When in doubt, ask for the ring's inner diameter in millimeters — that measurement is universal.
Frequently Asked Questions
How do I read a ring size chart?
Find the sizing system you know (US, UK, or EU) in the chart header. Locate your size in that column, then read across the row to see equivalents. For example, US 7 corresponds to UK N, EU 54.3, a 17.3mm diameter, and a 54.4mm circumference.
What ring size chart should I use for online shopping?
Use a chart that shows millimeter measurements (diameter or circumference) since these are universal. If the retailer lists sizes in a system you don't know, find your size in mm first, then look up the corresponding size in their system. Our chart covers all major systems side by side.
Are ring size charts the same for men and women?
Yes. Unlike shoe sizing, ring size charts are unisex. A US size 7 is the same physical ring regardless of whether it's for a man or a woman. The only difference is that men tend to wear larger sizes (average 9-10) while women tend to wear smaller sizes (average 6-6.5).
How do UK ring sizes work with letters?
The UK system uses letters A through Z, where each letter represents a specific inner circumference. After Z, sizes continue as Z+1, Z+2, etc. The spacing between letters is approximately 1.25mm in circumference. UK size F corresponds to US 3, and Z corresponds to US 13.
What is the most accurate way to determine ring size?
A jeweler's mandrel (the metal cone tool) is the gold standard. For at-home measurement, wrapping a thin strip of paper around your finger and measuring the circumference in millimeters is the most reliable method. Measure 3-4 times at different times of day and use the average.
Can I print this ring size chart?
Yes. Click the Print Chart button above the table to generate a clean, printer-friendly version. The printed chart includes all sizes from US 3 to US 15 with US, UK, EU, diameter, and circumference columns. It makes a handy reference to take to a jewelry store.