A Guide to Determining Your Ring Size

Yellow golden ring with a diamond

Are you looking for the perfect ring but don’t know your size? Perhaps you’re getting ready to propose and need to figure out what size engagement ring to buy? We’ve compiled a list of useful tips that make finding the right ring size quick and easy!

When buying a ring online, it’s especially important to know the correct size since you can’t try it on beforehand. You don’t want to have to send your new purchase back because it isn’t a perfect fit!

If you already know your ring size in one country, jump ahead to our ring size chart. It will help you convert your size into other common international systems.

Table Of Contents

Things to Know Before Measuring Your Finger

Before you figure out your ring size, there are a few things you should know:

Your fingers vary in size on each hand. They may be larger or smaller depending on whether you’re left or right-handed. Make sure you measure the finger you want to wear your ring on!

What’s more, your fingers change sizes depending on the temperature: They shrink in the cold and swell in heat. The time of day can also have an effect. Fingers tend to be larger at night than they are in the morning.

Certain medicines, injuries, and hormonal changes, such as those experienced in pregnancy, can also lead to swollen hands and fingers.

Our tip: Measure your finger in its “normal” state! Ideally, try to measure your finger at different times of day to determine its average circumference.

Measuring tape with ring

Determining Ring Size Using Your Finger’s Circumference

If you don’t have any rings that fit, you can quickly figure out your ring size using three simple items: a thread, a ruler, and a pen!

How it works:

Use our chart to look up your ring size!

Using a Ring’s Diameter to Calculate Its Size

Already own a ring that fits just right? Use a ruler to measure its diameter. Our tip: Make sure the reference ring is a similar shape to the ring you want to purchase.

You can then use our chart to see what size that diameter corresponds to.

Ring-sizing gauge with ring models

Having a Jeweler Determine Your Ring Size

You can get the most exact results by having an expert measure your ring size. Jewelers determine the size by putting a ring on a ring stick or mandrel. They will have a ring-sizing gauge as well if you don’t have a reference ring.

Jeweler puts a ring on a mandrel

Finding out Your Partner’s Ring Size in Secret

Are you looking to propose but want to surprise your loved one with an engagement ring? Then you better know their ring size! What could be worse than an engagement ring that’s too small or large?

To keep your significant other in the dark, try asking their friends or family. With any luck, one of them will know their ring size. Alternatively, you could sneak off with one of your partner’s rings and measure it when they’re away.

If you don’t have much time, press the ring into clay or putty and use the impression to make the measurement later.

Ideally, you’ll have enough time to figure out the diameter using the original ring. You can then refer to the chart below to determine the right size.

With these tips, you’ll be buying the perfect engagement ring in no time! Explore some exclusive listings here: To our engagement rings

A man puts an engagement ring on his bride-to-be's finger

How do international ring sizes differ?

There are five common systems for ring sizing. The United States, Canada, and Mexico use a numerical scale with half and quarter sizes.

Japan, China, and India also utilize a numerical scale, but it only has whole sizes. Countries like Italy, Spain, and Switzerland use a system that takes the circumference in millimeters and subtracts 40. Germany, France, and Scandinavia follow ISO standards, with the size matching the ring’s internal circumference. Finally, some countries use an alphabetical system. These include the UK, Ireland, and Australia. Find out your ring size in different countries using our sizing chart.

International Conversion Chart

This sizing chart will help you determine the right ring size using the ring’s internal diameter. You can also use it to determine your ring size in another country.

Note: The average American woman has a ring size of 6 or 6.5, while the average man has a size between 8 and 10.5.


(in mm)

ISO (Germany, France, etc.)


Italy, Spain, Netherlands, etc.


UK, Ireland, Australia, etc.


US, Canada, Mexico


Japan, China, etc.


12 A 0.5
12.5 40 0 B 1 1
12.9 40.5 0.5 C 1.5
13.4 41.5 1.5 D 2 2
13.8 43 3 E 2.5 3
14.2 44.5 4.5 F 3 4
14.6 45.5 5.5 G 3.5 5-6
15 47 7 H 4 7
15.4 48 8 I 4.5 8
15.8 49.5 9.5 J 5 9
16.2 50.5 10.5 K 5.5 10-11
16.5 52 12 L 6 12
17 53.5 13.5 M 6.5 13
17.5 54.5 14.5 N 7 14
17.8 56 16 O 7.5 15
18 56.5 16.5 P 8 16
18.5 58.5 18.5 Q 8.5 17
19 59.5 19.5 R 9 18
19.5 61 21 S 9.5 19
19.9 62.5 22.5 T 10 20
20.3 63.5 23.5 U 10.5 22
20.5 65 25 V 11 23
21 66 26 W 11.5 24
21.5 67.5 27.5 X 12 25
22 69 29 Y 12.5 26
22.5 70 30 Z 13 27

Download our ring size chart as a PDF for easy reference in the future!

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Closeup of gold rings with diamonds

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