How to Measure Your Ring Size at Home
There are three reliable ways to find a ring size without visiting a jeweller. The first one — using this page — is the fastest, because your screen has already been calibrated to real-world millimetres.
Match an existing ring
Take a ring that fits the correct finger, lay it on the golden circle above, and adjust until the circle fills the inside of the band exactly. The inner diameter is what determines ring size, so ignore the metal itself.
String and ruler
Wrap a thin strip of paper or thread snugly around the base of the finger, mark where it overlaps, and measure the length in millimetres. That number is the circumference — type it into the converter above.
Measuring a ring secretly
Planning a surprise proposal? Borrow a ring your partner wears on the correct hand, press it gently into a bar of soap or trace the inside on paper, then match the circle on this page to your tracing.
Getting an accurate result
- Calibrate first. The single most important step. A bank card is 85.60 mm wide everywhere in the world, which is why we use it as the reference.
- Measure warm fingers. Fingers shrink in the cold and swell in heat. Late afternoon at room temperature gives the truest reading.
- Mind the knuckle. If your knuckle is noticeably larger than the base of your finger, measure both and choose a size in between.
- Wide bands run tight. For bands wider than 6 mm, go up half a size for comfort.
- Left and right differ. Your dominant hand is usually about half a size larger. Measure the exact finger the ring will be worn on.
Which finger is which size?
For women, the most common engagement ring sizes fall between US 5 and US 7 (about 15.7–17.3 mm inner diameter). For men, wedding bands most often land between US 9 and US 11 (19.0–20.6 mm). These are averages, not rules — hand size varies far more than height or build suggests, which is exactly why measuring beats guessing.
Frequently Asked Questions
Is an online ring sizer accurate?
Yes — once calibrated. After you match the on-screen card to a real bank card, every millimetre on this page corresponds to a real millimetre. The circle method reads inner diameter directly, which is the same measurement a jeweller's mandrel gives.
What is the average ring size?
The most common size for women is US 6 to 6.5 (about 16.5–16.9 mm), and for men US 10 (about 19.8 mm). Averages vary slightly by country and by finger.
How do I convert my ring size between US, UK and EU?
Use the converter above, or find your measurement in the chart. As a rule of thumb: the EU/ISO size equals the inner circumference in millimetres, and each full US size step equals about 0.81 mm of diameter.
Can I measure my ring size with my phone?
Yes. This tool works on any phone or tablet. Calibrate with a bank card the same way, then place your ring directly on the phone screen. Phone screens are glass, so a ring will not damage them with gentle placement.
Should I size up or down if I'm between sizes?
Size up. A slightly loose ring can be worn comfortably or resized down cheaply, while a tight ring is uncomfortable and harder to remove. Rings should slide over the knuckle with light resistance and sit snugly at the base.
Do Indian and Japanese ring sizes use the same numbers?
They are very close and are usually listed in the same column. Both are numeric systems where, for example, size 14 corresponds to roughly a 17.3 mm inner diameter (US 7).