Ring Size Calculator
Estimate your ring size using the inside diameter of an existing ring or your finger circumference.
Your result is based on the closest standard ring size.
Finding the right ring size can make a big difference in how comfortably a ring fits. Our Ring Size Calculator lets you estimate your ring size using either the inside diameter of a ring you already own or the circumference of your finger.
Enter your measurement, select the correct unit, and the calculator will provide an estimated US ring size, along with approximate UK, Australian, and EU sizing equivalents.
Keep in mind that this tool provides an estimate. For the most accurate fit, use a professional ring-sizing tool or have your finger measured by a jeweler.
How to Use the Ring Size Calculator
You can calculate your ring size in two simple ways.
Method 1: Measure an Existing Ring
If you already have a ring that fits the intended finger comfortably, measuring its inside diameter can be an easy way to estimate your size.
- Choose Ring Diameter.
- Measure the inside of the ring from one inner edge directly across to the opposite inner edge.
- Enter the measurement into the calculator.
- Select millimeters, centimeters, or inches.
- Click Calculate My Ring Size.
Make sure you measure the inside diameter rather than the outside diameter of the ring.
Method 2: Measure Your Finger Circumference
You can also measure around the finger where you plan to wear the ring.
- Choose Finger Circumference.
- Wrap a flexible measuring tape around the base of your finger.
- If you don't have measuring tape, use a thin strip of paper or a piece of string.
- Mark where the ends meet.
- Measure the marked length with a ruler.
- Enter the measurement and select the correct unit.
- Click Calculate My Ring Size.
The measurement should be snug but not tight. You should be able to remove the measuring strip without difficulty.
How Ring Sizes Are Measured
Ring sizes are based on the dimensions of the finger or the inside of the ring.
In the United States and Canada, ring sizes are expressed using numbers such as 6, 7, 8, and 9, with half sizes also commonly available.
Other countries use different sizing systems. For example, UK and Australian ring sizes generally use letters, while European sizing commonly uses numbers based on the circumference of the ring.
Because sizing systems differ between countries and manufacturers, always check the individual jeweler's sizing chart when purchasing a ring internationally.
Ring Size Conversion Chart
Here is a quick reference for common ring sizes:
| US Size | UK Size | EU Size | Inside Diameter | Inside Circumference |
|---|---|---|---|---|
| 5 | J | 49 | 15.7 mm | 49.3 mm |
| 5.5 | K | 51 | 16.1 mm | 50.6 mm |
| 6 | L | 52 | 16.5 mm | 51.9 mm |
| 6.5 | M | 53 | 16.9 mm | 53.1 mm |
| 7 | N | 54 | 17.3 mm | 54.4 mm |
| 7.5 | O | 56 | 17.7 mm | 55.7 mm |
| 8 | P | 57 | 18.1 mm | 57.0 mm |
| 8.5 | Q | 58 | 18.5 mm | 58.3 mm |
| 9 | R | 60 | 18.9 mm | 59.5 mm |
| 9.5 | S | 61 | 19.4 mm | 61.0 mm |
| 10 | T | 62 | 19.8 mm | 62.1 mm |
Note: International ring-size conversions are approximate. Different jewelers may use slightly different sizing charts.
Tips for Getting a More Accurate Ring Size
Your finger size can change throughout the day, so taking a little extra care when measuring can improve your result.
Measure more than once
Take your measurement two or three times. If you get different results, use the measurements to determine a consistent range rather than relying on one reading.
Measure when your fingers are at a normal temperature
Cold temperatures can temporarily make fingers smaller, while heat can cause them to swell. Avoid measuring immediately after being outside in very cold or hot conditions.
Don't pull the measuring strip too tightly
A strip that is pulled tightly around your finger can produce a size that is too small. It should fit comfortably around the finger.
Consider the ring width
Wide rings can feel tighter than narrow bands. If you are buying a wide-band ring, you may need a slightly larger size than the calculator's estimate.
Measure the exact finger
Your fingers are not necessarily the same size on both hands. If you're buying a ring for your right ring finger, measure that finger rather than assuming your left ring finger is identical.
What If You Are Between Two Ring Sizes?
If your measurement falls between two standard sizes, don't assume that one size will always be correct.
The best choice can depend on the ring's design, band width, finger shape, and personal preference. A professional jeweler can help you determine which size provides the best fit.
For an important purchase, especially an expensive or custom ring, professional sizing is recommended.
Is Ring Size the Same in Every Country?
No. Ring-size systems vary between countries.
The US and Canada commonly use numerical sizes, while the UK and Australia generally use letter-based sizes. European sizing commonly uses numbers based on ring circumference.
This means a US size 7 does not simply correspond to the number 7 in every country.
Our calculator provides approximate UK/Australia and EU equivalents to make international sizing easier to understand, but you should always verify the conversion against the retailer's own sizing chart before ordering.
Diameter vs. Circumference: Which Method Is Better?
Both methods can be useful.
Measuring an existing ring's inside diameter can be convenient if you already own a ring that fits the same finger comfortably.
Measuring your finger circumference can be useful when you don't have a suitable ring available.
For either method, measurement accuracy is important. A small measurement error can change the estimated ring size, particularly when your measurement falls close to the boundary between two sizes.
How Accurate Is This Ring Size Calculator?
This calculator provides an estimated ring size based on standard measurement values. It should not be considered a substitute for professional ring sizing.
Your actual ideal size can vary because of finger swelling, measuring technique, ring width, finger shape, and differences between jewelry manufacturers.
For the best possible fit, measure carefully and compare your result with the sizing information provided by the jeweler or ring manufacturer.