Ring sizer

Step 1: calibrate with a bank card

Turn a phone sideways (the card’s 85.6 mm long side is wider than a phone screen held upright). Lay any payment or ID card on the screen over the dashed box and move the slider until the box is exactly as wide as the card.

3 pixels per mm assumed until you calibrate.

Step 2: match a ring that fits

Lay the ring on the circle and move the slider until the circle just fills the inside of the band. Then read the size.

Your size

17.3 mm across · US 7 · UK N½ · EU 54.5 · Japan 14

  • US / Canada7
  • UK / AustraliaN½
  • EU / ISO54.5
  • Japan14
  • Inner circumference54.3 mm

Browser zoom must stay at 100% after calibrating. A phone laid flat and turned sideways is easier than a laptop screen; a tablet is easiest.

Convert a size

Type 7, 7.5 or 7½ for US; L or L½ for UK; 54 or 54.5 for EU; 14 for Japan.

In every scale

UK N½

US 7 on the other scales

US 7 is an inner circumference of 54.4 mm and an inner diameter of 17.32 mm. Nearest sizes: US 7, UK N½, EU 54.5, Japan 14; the brackets show how far each is from exact.

  • US / Canada 7 (exact)
  • UK / Australia N½ (exact)
  • EU / ISO 54.5 (exact)
  • Japan 14 (exact)
  • Inner diameter 17.32 mm (0.682 in)
  • Inner circumference 54.4 mm (2.14 in)
USDiameter mmCircumference mmUKEU / ISOJapan
314.0744.2F½444
3½14.4745.5G½45.55
414.8846.8H½477
4½15.2948I½488
515.6949.3J½49.59
5½16.150.6K½50.510
616.5151.9L½5212
6½16.9153.1M½5313
7 ◀17.3254.4N½54.514
7½17.7355.7O½55.515
818.1357P½5716
8½18.5458.2Q½5818
918.9559.5R½59.519
9½19.3560.8S½6120
1019.7662.1T½6221
10½20.1663.3U½63.522
1120.5764.6V½64.524
11½20.9865.9W½6625
1221.3867.2X½6726
12½21.7968.5Z68.527
1322.269.7Z+169.529
13½22.671Z+27130
1423.0172.3Z+372.531
14½23.4273.6Z+473.532
1523.8274.8Z+57533

Sizes are the nearest on each scale to the measurement; a jeweller’s gauge is the final word. Nothing you do here is sent anywhere.