# Ring Size Calculator > Determine ring size from finger circumference or existing ring diameter. Convert between US, UK, EU, and Asian ring size scales. **Category:** Everyday Life **Keywords:** ring size, ring size calculator, finger size, ring measurement, US ring size, UK ring size, EU ring size, Japanese ring size, ring conversion **URL:** https://complete.tools/ring-size-calculator ## How to measure your finger There are two reliable methods for measuring your finger at home: **Method 1: String or Paper Strip (Circumference)** Wrap a thin strip of paper or a piece of non-stretchy string around the base of your finger. Mark where the end meets the strip, then measure the length in millimeters with a ruler. This gives you your finger circumference directly. This is the most accurate home measurement method. **Method 2: Measure an Existing Ring (Diameter)** If you already own a ring that fits well, place it on a ruler and measure the inner diameter — the distance across the inside of the ring in a straight line through the center. Enter this diameter into the calculator to find your size. **Tips for accurate measurement:** - Measure at the end of the day, when fingers are slightly larger - Avoid measuring when hands are cold or hot, as temperature changes finger size - Measure the specific finger and hand you plan to wear the ring on (left and right hands can differ) - If your knuckle is larger than the base of your finger, measure both and choose a size between them - Wide band rings generally require going up half a size for comfortable fit ## US vs UK vs EU vs Asian ring sizes The four major ring sizing systems used worldwide each take a different approach: **US / Canada Sizing** The American system uses numbers from 3 to 13 (with half sizes) for standard adult rings. Size 7 is the most common size for women, and size 10 is common for men. The system has no mathematical relationship to the circumference — it is purely an arbitrary scale developed by American jewelers. **UK / Australia / New Zealand / Ireland / South Africa Sizing** The British system uses letters of the alphabet starting from A. Letters correspond to specific circumferences in 1.25 mm increments. The most common women's size falls around L–N, and common men's sizes around R–T. **EU / ISO Sizing (Continental Europe)** The European system is the most logical: the size number equals the inner circumference of the ring in millimeters. A EU size 54 ring has an inner circumference of 54 mm. This is the international standard (ISO 8653) and is used across France, Germany, Spain, Italy, the Netherlands, and Scandinavia. **Asian Sizing (Japan / China / Hong Kong)** Japan and China use a numeric system similar to the US system but with different numbers. Japanese sizes range from 1 to 30 for standard adult rings. The Japanese system is widely used across East Asia and Southeast Asia. A Japanese size 14 corresponds to a US size 7 and EU size 54. ## Tips for accurate measurement Getting an accurate ring size measurement requires attention to a few key details: - **Time of day matters:** Fingers are typically smallest in the morning and largest at the end of the day. For everyday rings, measure in the afternoon or evening. - **Temperature affects size:** Fingers swell in heat and shrink in cold. Avoid measuring immediately after exercise, a hot shower, or in very cold weather. - **Dominant hand is larger:** Most people's dominant hand is slightly larger. If buying a ring for your right hand, measure your right hand. - **Knuckle consideration:** If your knuckle is significantly wider than the base of your finger, choose a size that slides over the knuckle and use a ring guard to keep it from spinning. - **Wide bands fit tighter:** A band wider than 6 mm will feel tighter than a narrow band of the same diameter. Go up half a size for wide-band rings. - **When in doubt, go larger:** It is easier to size a ring down than to size it up. Buying slightly large and having it sized by a jeweler is often cheaper than re-sizing after a purchase. - **Professional sizing:** For important purchases like engagement rings or wedding bands, visit a local jeweler for professional finger sizing before ordering. ## FAQs **Q:** What is the most common ring size for women? **A:** The average women's ring size in the United States is size 6 to 7, corresponding to a finger circumference of about 51.9–54.4 mm. EU sizes 52–54 and UK sizes L–N cover the same range. **Q:** What is the most common ring size for men? **A:** The average men's ring size in the United States is size 10 to 11, corresponding to a circumference of about 62.1–64.6 mm. EU sizes 62–65 and UK sizes T–V cover this range. **Q:** Can I use a ruler to measure my ring size? **A:** Yes. Wrap a strip of paper around your finger, mark the overlap point, then lay the strip flat and measure it with a ruler. This gives you the circumference in millimeters. Alternatively, measure the inside diameter of an existing ring in millimeters. **Q:** What if I am between two sizes? **A:** If your measurement falls between two standard sizes, it is generally better to go up to the larger size. A ring that is slightly too large can be worn with a ring guard, while a ring that is too tight is uncomfortable and difficult to remove. **Q:** Do ring sizes vary between countries? **A:** The ring itself is the same physical object worldwide — what varies is the numbering system used to describe it. A US size 7, UK size N, EU size 54, and Japanese size 14 are all the same ring. This calculator converts between all four systems automatically. **Q:** How accurate is this calculator? **A:** This calculator uses closest-match conversion based on the ISO 8653 standard and published ring size charts from major jewelry associations. The accuracy depends entirely on the accuracy of your input measurement. For important purchases, always confirm with a professional jeweler. **Q:** Do engagement rings have different sizing than regular rings? **A:** The sizing is the same, but engagement rings and wedding bands are often wider than fashion rings. For bands wider than 6 mm, it is recommended to go up half a size to account for the different fit feel of a wide band. **Q:** What is an EU ring size? **A:** EU ring sizes directly represent the inner circumference of the ring in millimeters. A EU size 54 ring has exactly 54 mm of inner circumference. This makes the EU system the simplest and most precise, and it is the basis for the ISO international standard. ## How to use 1. Choose your input method — select "Circumference" if you have wrapped a string or strip around your finger, or "Diameter" if you are measuring an existing ring from the inside. 2. Select your unit — millimeters (mm) for most of the world, or inches if your ruler only shows imperial units. 3. Enter your measurement in the number field. 4. Click "Calculate Ring Size" to see your results. 5. The calculator will display your US size prominently, plus equivalent UK letter, EU number, and Asian/Japanese size. 6. It also shows the circumference and inner diameter used for the calculation, so you can verify the numbers are correct. --- *Generated from [complete.tools/ring-size-calculator](https://complete.tools/ring-size-calculator)*