# Ring Size Calculator

Find your ring size from finger circumference or diameter in mm. Converts between US, UK, and EU ring size scales. Perfect for buying rings online.

## What this calculates

Buying a ring online? Measure your finger circumference or a ring's inner diameter in millimeters, and this calculator converts to US, UK, and EU ring sizes instantly. Essential for engagement rings, wedding bands, and online jewelry shopping.

## Inputs

- **Finger Circumference** (mm) — min 36, max 90 — Wrap a string around your finger, then measure the string in mm
- **Measurement Type** — options: Circumference, Inner Diameter

## Outputs

- **US / Canada Size** — formatted as text
- **UK / Australia Size** — formatted as text
- **EU / French Size** — formatted as text
- **Inner Diameter** (mm)
- **Circumference** (mm)

## Details

How to measure your finger:

  - Wrap a strip of paper or string snugly around the base of your finger

  - Mark where the ends meet

  - Measure the length in millimeters - this is your circumference

  - Alternatively, measure the inner diameter of a ring that fits well

Tips for accurate measurement:

  - Measure at the end of the day when fingers are slightly larger

  - Measure at room temperature (cold shrinks fingers)

  - Account for knuckle size - the ring must pass over it

  - Measure multiple times and average the results

## Frequently Asked Questions

**Q: What is the most common ring size?**

A: For women in the US, the most common ring size is 6-7 (circumference 51-55 mm). For men, the most common size is 9-10 (circumference 60-63 mm). However, individual finger sizes vary widely.

**Q: Should I size up or down if between sizes?**

A: Generally, size up. It is easier to add a ring guard to a slightly loose ring than to resize a tight one. For wide bands (6mm+), go up half a size as they fit more snugly than thin bands.

**Q: Do fingers change size?**

A: Yes, finger size fluctuates due to temperature (cold = smaller), time of day (larger in the evening), hydration, salt intake, exercise, and weight changes. Measure at the end of a normal day for the most reliable size.

**Q: Can rings be resized?**

A: Most rings can be resized 1-2 sizes up or down by a jeweler. However, rings with stones all around (eternity bands), tungsten carbide rings, and titanium rings cannot typically be resized. The cost ranges from $20-$100+ depending on the metal and complexity.

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Source: https://vastcalc.com/calculators/everyday/ring-size
Category: Everyday Life
Last updated: 2026-04-21