How to Measure Your Ring Size at Home (US, UK, EU Charts Included)

Your ring size is just a length: the inner circumference of the band in millimeters — and that number is literally your EU/ISO size. Measure it with a strip of paper in two minutes, then read every other system off the chart: 54 mm ≈ US 7 ≈ UK N. The ring size converter does the mapping instantly, in your browser.

The three sizing systems, one measurement

Every system labels the same physical thing — the ring’s inner size:

System	What the number means	Example
EU / ISO 8653	inner circumference in mm	54.4
US / Canada	numeric scale, 0.5 steps	7
UK / Australia	letters A–Z, half sizes	N
Jewelers’ mm	inner diameter	17.3 mm

The scales lock together arithmetically: each half US size = one UK letter = ~1.28 mm of circumference. That’s why a single paper-strip measurement resolves everything — the converter accepts circumference, diameter, US or UK and returns the rest.

Measuring at home: the paper strip method

1. Cut a strip of paper ~5 mm wide (string works but stretches — paper is more accurate).
2. Wrap it around the base of the finger, snug but not tight, and mark exactly where it overlaps.
3. Measure from end to mark in millimeters. That’s your EU size.
4. Check the knuckle: if it’s clearly larger than the base, measure it too and pick a size between the two.

Measuring an existing ring instead

For a ring that already fits the target finger: place it on a ruler and measure the inner diameter (widest inside distance) in mm, then use the converter’s diameter mode. 17.3 mm → US 7. This is also the secret-proposal method: borrow a ring they wear on the ring finger of the correct hand (left and right differ by about half a size for most people) and measure it — or press it gently onto paper and trace the inner circle.

Quick reference chart

US	UK	EU (circ. mm)	Diameter mm
4	H	46.8	14.9
5	J	49.3	15.7
6	L	51.9	16.5
7	N	54.4	17.3
8	P	57.0	18.1
9	R	59.5	19.0
10	T	62.1	19.8
11	V	64.6	20.6
12	X	67.2	21.4

The full chart with half sizes covers US 3–13.

Common ring-sizing mistakes

1. Measuring with stretched string — it reads large; the ring arrives loose. Use paper.
2. Ignoring the knuckle — a ring must pass it. If knuckle ≫ base, size between them and consider a ring with a slightly euro-shaped (flattened) bottom.
3. Cold-hands measuring — winter measurements run half a size small.
4. Forgetting band width — wide bands (6 mm+) need ~half a size up.
5. Assuming both hands match — they don’t; measure the hand that will wear it.

Quick summary

Wrap paper around the finger, measure the overlap in millimeters — that circumference is your EU size, and the converter maps it to US and UK instantly (54 mm ≈ US 7 ≈ UK N). Measure at day’s end, account for the knuckle and band width, and when in doubt between two sizes, take the larger.

Conversions use the standard jewelers’ chart on the ISO 8653 circumference scale. Sizes and measurements you enter never leave your browser — try the ring size converter, and see the shoe and bra converters for the rest of the sizing family.