Skip to content
ringsizerchart

Every ring size, US 3 to 15

One spec sheet for every US half size from 3 to 15: inside diameter and circumference in mm and inches, UK, EU, Japanese and Swiss equivalents, the quarter sizes either side and wide-band ordering. A size 8 is 18.13 mm inside, UK P½, EU 57. Pick a size to open it at 1:1.

Try

Lay a ring that fits flat on the circle and size the red line until it just touches the inside edge of the band all the way round: on a phone, slide sideways anywhere on the stage or hold the buttons below; on a computer, drag the edge, scroll or press ← →. The gold ring is the band’s wall: don’t match its outside.

US 818.13 mm · 0.714" inside · 57.0 mm round
Inside diameter18.13 mm
Band wall1.8 mm
Jump to US

Full chart 25 rows

Sort any column, download it as CSV or print it. Click a row to show it at 1:1.

Every ring size spec sheet

25 rows
Download CSV
US ring sizes 3 to 15 in half sizes with inside diameter in mm and inches, inside circumference in inches and who usually wears each size
Actions
14.070.5541.74a petite size
14.470.5701.79a petite size
14.880.5861.84a smaller women’s size
15.290.6021.89a smaller women’s size
15.690.6181.94a smaller women’s size
16.100.6341.99a smaller women’s size
16.510.6502.04in the main women’s range (most women wear 6 to 8½)
16.910.6662.09in the main women’s range (most women wear 6 to 8½)
17.320.6822.14the most common women’s ring size in jewellers’ order data
17.730.6982.19the upper half of the women’s range and below most men’s sizes (9 to 12)
18.130.7142.24the upper half of the women’s range and below most men’s sizes (9 to 12)
18.540.7302.29the upper half of the women’s range and below most men’s sizes (9 to 12)
18.950.7462.34where the ranges meet
19.350.7622.39where the ranges meet
19.760.7782.44the most common men’s ring size in jewellers’ order data
20.160.7942.49squarely in the men’s range (most men wear 9 to 12)
20.570.8102.54squarely in the men’s range (most men wear 9 to 12)
20.980.8262.59squarely in the men’s range (most men wear 9 to 12)
21.380.8422.64squarely in the men’s range (most men wear 9 to 12)
21.790.8582.70a large men’s size above the usual 9 to 12 range
22.200.8742.75a large men’s size above the usual 9 to 12 range
22.600.8902.80a large men’s size above the usual 9 to 12 range
23.010.9062.85a large men’s size above the usual 9 to 12 range
23.420.9222.90a large men’s size above the usual 9 to 12 range
23.820.9382.95a large men’s size above the usual 9 to 12 range

05 / Field guide

Every size,
its own sheet.

Each US half size from 3 to 15 has a spec sheet with the numbers jewellers and buyers ask for: inside diameter and circumference in millimetres and inches, the UK, EU, Japanese and Swiss equivalents, the quarter sizes either side, what to order for wide bands, and blank lengths for making a band.

Six systems, one measurement

Every ring size system measures the same thing: the inside of the band. The US and Canadian scale starts at 11.63 mm inside diameter for size 0 and adds 0.8128 mm (0.032") per whole size, so each quarter size is about 0.2 mm. There is no ASTM or ANSI standard behind it; it is a trade scale that ring mandrels and sizing gauges follow.

ISO 8653, used across continental Europe, simply names a ring by its inside circumference in millimetres, so EU 54 is a 54 mm loop. Swiss, Italian and Spanish sizes are that number minus 40. The UK, Ireland and Australia use letters; since BS 6820 (1987) each letter is 1.25 mm of circumference, with C at 40 mm, and half letters in between. Japan uses numbers 1 to 30 that step about a third of a millimetre of diameter.

US inside Ø (mm) = 11.63 + 0.8128 × size · circumference = π × Ø · EU = circumference rounded · Swiss = EU − 40

Which size is common?

Jewellers who publish their order data report that most women wear US 6 to 8½, with 7 the most common, and most men 9 to 12, with 10 the most common. Sizes 3 to 5 are typical for little fingers, midi rings and teenagers; 12 and up for larger men’s hands and thumb rings.

Quarter sizes and tolerance

Each quarter size is about 0.2 mm of diameter, 0.64 mm round. Ring mandrels and finger gauges are made to roughly that tolerance, and a finger changes by more than that across a day. If you measure between two quarter sizes, choose the larger for a wide band and the smaller for a narrow one. A jeweller can usually stretch a plain gold or silver band by about half a size, so being a quarter out is rarely a disaster.

Opening a sheet at 1:1

Each sheet opens the 1:1 ring circle at its own size, so you can lay a ring on it and see at a glance whether it is that size, a little bigger or smaller. The neighbouring-size buttons step a quarter at a time.

For the bench

Every sheet lists blank lengths for wire and sheet from 1 to 2.5 mm thick, worked out from π × (inside diameter + thickness), the length of the band’s middle line. Cut a little long, file the ends square and true the band on a mandrel after soldering.

Blank length = π × (inside Ø + thickness)

Questions

Answered plainly.

01What is the most common ring size?+

For women, US 7 (17.32 mm inside); for men, US 10 (19.76 mm), according to jewellers’ published order data.

02What is a size 8 ring in mm?+

A US size 8 is 18.13 mm (0.714") across the inside and 57.0 mm round. It is UK P½, EU 57 and Japan 16.

03What is the smallest adult ring size?+

Adult rings are rarely made below US 3 (14.07 mm). Sizes 3 to 4 are usual for little fingers and midi rings worn above the knuckle.

04What is the difference between a size 9 and 9.5?+

A half size is 0.41 mm of inside diameter and 1.28 mm of circumference: 18.95 mm against 19.35 mm.

05How do I find my ring size in inches?+

Divide the inside diameter in millimetres by 25.4. A US 7 is 0.682" across and 2.14" round.

06Are ring sizes the same for men and women?+

Yes. A size is a physical measurement; only the usual ranges differ.

Ring sizesUS · inside Ø mm

Carat sizes

Necklace lengths