73% guess ring sizes wrong.
Free Forever·30-Second Result·Works on Any Device

Ring Size Calculator

Place your ring. We measure it in real-time. Get every international size instantly.

Calibrate your screen

For accurate measurements, we need to know your screen's resolution. Choose one method:

How It Works

01

Calibrate your screen

Select your device or use a credit card — takes 5 seconds

02

Place your ring

Set your ring on the circle and resize to match the inner edge

03

Get your size

Instant results in US, UK, EU, Indian, and Japanese formats

Need to convert between countries?

Ring Size Converter →

See the full chart?

International Size Chart →

Common questions

FAQ →

How to Use Our Ring Size Calculator

Our free ring size calculator gives you an accurate measurement in under 30 seconds — no app download, no printable template, and no trip to the jeweler. It works on any device with a screen: phone, tablet, or laptop. Start by calibrating your display (choose your device model or hold a credit card to the screen), then either place an existing ring on the on-screen circle or enter your finger circumference measured with string. The tool instantly converts your measurement into US, UK, EU, Indian, and Japanese ring sizes, along with precise diameter and circumference in millimeters.

Whether you need a ring size calculator in cm, a ring size calculator in inches, or want to convert ring circumference to size, our tool handles every unit. The ring size converter page lets you cross-reference between systems if you already know one size and need another.

How to Measure Ring Size at Home

Wondering how to measure ring size at home? You have two reliable options. Option 1 — Existing ring method: take a ring that already fits the target finger, place it flat on your screen, and resize the on-screen circle until it matches the inner edge. Option 2 — String or paper method: cut a thin strip of paper or string, wrap it around the base of your finger (snug but not tight), mark the overlap, then measure the length in millimeters. Enter that number into our calculator and get your size instantly. For more detail, read our full guide on how to measure ring size at home.

For the most accurate result, measure in the evening when fingers are at their widest. Avoid measuring after exercise, a hot shower, or in very cold weather — your fingers can fluctuate by up to half a size throughout the day.

Ring Size Chart — US, UK, EU, India & Japan

Every ring size corresponds to a specific inner diameter and circumference in millimeters. A US size 6, for example, has an inner diameter of about 16.5 mm and a circumference of roughly 51.8 mm. The UK uses an alphabetical system (A–Z), while the EU system equals the circumference in millimeters — making EU 52 a ring with a 52 mm inner circumference. The Indian and Japanese systems both use numbered scales, but they are not interchangeable — an Indian size 12 is different from a Japanese size 12.

View the complete comparison on our ring size chart, which includes every half-size from US 3 to US 15 with ring size in mm for both diameter and circumference. It's the most complete printable ring size chart available online — and unlike printable PDFs, it doesn't require calibration or scaling.

Average Ring Sizes for Men and Women

The average ring size for women in the United States is US 6 to US 7. Engagement rings most commonly sell in size 6 to 6.5. If you're buying a surprise ring, US 6 is a safe starting point — most jewelers can resize one to two sizes in either direction.

For men, the average ring size falls between US 9 and US 11, with US 10 being the most frequently purchased. Men's wedding bands are often wider (6–8 mm), which means you may need to go up half a size from your measured result. Our calculator includes a wide-band adjustment toggle, and you can learn more in our wide band ring sizing guide. For a deeper dive into sizing differences, explore our ring size guide for men and women.

Have a question about sizing? Check out our ring size FAQ for answers to the most common questions, from how to find your ring size secretly to understanding why your ring feels tighter in summer.

Frequently Asked Questions

How do I measure ring size without an existing ring?
If you don't have a ring to measure, use the paper strip method: wrap a thin strip around the base of your finger, mark where it overlaps, then measure the length in millimeters. Enter that number in our ring sizing tool under "I Don't Have a Ring." For the most accurate reading, measure at room temperature in the evening when fingers are at their largest.
What is the most reliable method to determine ring size?
The most reliable method is using a professional ring mandrel or having a jeweler measure you in-store. For at-home accuracy, place an existing ring on our on-screen ring sizer and resize the circle to match the inner edge — this method is accurate to within ±0.5mm when your device is properly calibrated. String measurement is the best fallback if you have no existing ring.
What are the three most common ways to figure out ring size?
The three most common methods are: (1) Place an existing ring on an online sizer like our ring size tool for an instant result. (2) String or paper method — wrap around your finger, measure the length, and enter the circumference. (3) In-store measurement — a jeweler uses a set of ring mandrels for the most precise result. Method 1 is fastest; method 3 is most precise.
How do I figure out what my ring size is right now?
The fastest way is to use our free ring size finder. If you have an existing ring, place it on screen and resize the circle to fit — you'll get your US, UK, EU, Indian, and Japanese size in seconds. If you have no ring, wrap a strip of paper around your finger, measure the length in millimeters, and enter it into the tool under "I Don't Have a Ring."
What should I do if I'm between two ring sizes?
If your measurement falls between two sizes, always choose the larger one. A slightly loose ring is far more comfortable than a tight one, and you can use a ring size adjuster insert to snug it up. This is especially important for wide band rings (6mm+), which naturally fit tighter. Our tool shows you the nearest standard size — if you're right on the border, round up.
Does ring size differ between fingers?
Yes — every finger on each hand is a different size. Your dominant hand's ring finger is typically about half a size larger than the same finger on your non-dominant hand, and adjacent fingers can differ by one to two full sizes. Always measure the specific finger you plan to wear the ring on with our ring measurement tool — never assume sizes transfer between fingers.
How does a men's ring size chart differ from a women's?
Men's and women's rings use the same US size scale (3–13), so the chart itself is identical — but the typical ranges differ. Women's rings most commonly fall between US 5 and US 8, with US 6–7 being most popular. Men's rings typically range from US 8 to US 13, with US 10 being most common. Men's rings also tend to be wider (6–8mm), which means the wide-band size-up rule applies more often. See our full size chart for exact mm measurements.
How accurate is online ring sizing compared to in-store?
A properly calibrated online ring sizer is accurate to within ±0.5mm in diameter — roughly half a US size. The critical step is calibration: use your device model or the credit card method to set the correct pixel density. In-store ring mandrels can achieve ±0.25mm accuracy. For everyday rings, online sizing is sufficient. For high-value pieces like engagement rings, we recommend confirming with a physical sizer after getting your online result from our tool.
How much does ring resizing typically cost?
Ring resizing typically costs $20–$60 for simple sizing up or down by one size at most jewelers. Resizing by two or more sizes, or working with precious metals like platinum, can cost $50–$150+. Some ring types — like eternity bands, tungsten, or titanium rings — cannot be resized at all. Most jewelers offer a free or discounted first resize within 30–60 days of purchase. Getting the right size the first time with our free tool is always cheaper.
Does ring size change when you gain or lose weight?
Yes — significant weight changes (roughly 4–5 kg / 10 lbs or more) can shift your ring size by half to a full US size. Fat distributes across the entire body, including the fingers. Rapid weight loss after pregnancy or dieting often causes rings to become loose; weight gain can make them tight. If your rings no longer fit comfortably after a body change, re-measure with our free tool and consult a jeweler about resizing.
Does finger size change with age?
Finger size tends to increase slightly with age for most people. After 40–50, joints can swell due to arthritis, and fingers may widen as skin loses elasticity. Men often see gradual growth through middle age; women may notice changes after menopause due to hormonal shifts and water retention patterns. If rings that fit well a decade ago now feel tight or loose, it's worth re-measuring — ring size is not a lifetime constant.
How do I use a printable ring size chart correctly?
A printable ring size chart must be printed at 100% scale — never "fit to page" or "shrink to margins," or the measurements will be wrong. After printing, verify accuracy by measuring the ruler printed on the chart. Then either place an existing ring over the circles to find a match, or wrap the paper strip around your finger. Our online ring size chart removes the printing step entirely and works on any device.
How does the Oura ring sizing process work?
Oura ships a free sizing kit containing plastic sizing rings (sizes 6–13) before you order. You wear the sizing rings for 24 hours to account for daily finger fluctuation — Oura recommends your largest comfortable fit because their ring is slightly thicker than a standard band. Smart rings cannot be resized after purchase, so accuracy matters. Oura sizes correspond roughly to US ring sizes, but always use their official kit rather than standard jewelry measurements.
How do smart ring sizes differ from jewelry ring sizes?
Smart rings (Oura, Samsung Galaxy Ring, RingConn) use the same numerical US size scale but have a thicker profile than standard jewelry bands — typically 2.5–3mm wall thickness versus 1–2mm for fashion rings. This means a ring that fits in jewelry size 7 may feel tight as a smart ring. Smart ring makers recommend ordering one size up if you're between sizes, and most provide a free sizing kit. Never use your jewelry ring size to order a smart ring without testing first.
See all ring size FAQs →