How to find your ring size

The most reliable way to find your ring size is to have a jeweler measure the finger with metal sizing rings, in a band close to the width you plan to order. At home, measure the inside diameter of a ring that already fits that finger and match it to the table below, or wrap a strip of paper around the finger, mark the overlap and measure the length as circumference. Measure at the end of the day when your hands are warm, and go up half a size for bands 6 mm or wider. We confirm your size in the proof before we make anything.

Three ways to measure

A jeweler’s sizing rings. Most jewelers will size you for free. Ask for a sizer in a width similar to the band you want, because a 2 mm sizer and an 8 mm band fit differently. Try it on more than once over a day if you can.

A ring that already fits. Use a ring worn on the same finger. Measure straight across the inside, at the widest point, in millimetres. That is the inside diameter. Find the closest diameter in the table.

Paper or string. Wrap a thin strip of paper snugly around the base of the finger, mark where it overlaps, and measure the length in millimetres. That is the circumference. Paper stretches less than string, so it is the better choice. Make sure it can slide over your knuckle; if your knuckle is much larger than the base of the finger, size for the knuckle.

Ring size chart: US, Japanese 号 and millimetres

US size	Inside diameter	Inside circumference	Japanese size (号)
4	14.88 mm	46.8 mm	7
4.5	15.29 mm	48.0 mm	8
5	15.69 mm	49.3 mm	9
5.5	16.10 mm	50.6 mm	10
6	16.51 mm	51.9 mm	12
6.5	16.91 mm	53.1 mm	13
7	17.32 mm	54.4 mm	14
7.5	17.73 mm	55.7 mm	15
8	18.13 mm	57.0 mm	16
8.5	18.54 mm	58.2 mm	18
9	18.95 mm	59.5 mm	19
9.5	19.35 mm	60.8 mm	20
10	19.76 mm	62.1 mm	21
10.5	20.16 mm	63.3 mm	22
11	20.57 mm	64.6 mm	24
11.5	20.98 mm	65.9 mm	25
12	21.38 mm	67.2 mm	26

We make rings in US sizes 3 to 15, including half sizes. The full range is in our size guide.

How US and Japanese sizes relate

US sizes go up in half steps of about 0.4 mm in diameter. Japanese sizes, written with 号 (gō), go up in whole steps of about a third of a millimetre. Because the steps are different, the two systems do not line up exactly, and some 号 sizes fall between two US half sizes. We round to the nearest half US size and the nearest whole 号, and every proof shows your size in both systems so you can check it.

If you are in Japan and already know your 号, choose it on our Japanese site and we convert it for production. If you are between sizes, tell us when you approve your proof.

Getting it right

• Measure when your hands are warm. Fingers are smaller in the cold and in the morning, and larger after exercise, in heat and late in the day.
• Measure the right finger on the right hand. Your dominant hand is usually slightly larger.
• Allow for width. Bands 6 mm and wider cover more of the finger and fit more snugly. Many people go up half a size. Our wedding band width guide covers this.
• Comfort fit feels a little looser. Our rings have a rounded inside edge that slides over the knuckle more easily. Comfort fit explained shows why.
• Don’t guess for a surprise. If the ring is a gift, borrow a ring they wear on that finger, or ask a friend or family member to find out.

If the size is wrong

We confirm your size in the proof before production, and you can change it there. After delivery, we offer one free resize within 30 days where the design allows. How far a ring can move depends on the design:

• Heirloom Scroll Ring: a continuous engraved pattern can be adjusted by up to one size; beyond that we re-engrave.
• Maile Wedding Band: up to one size without re-engraving.
• Koa Inlay Ring and Koa Inlay Wedding Band: up to half a size, because the wood inlay limits how far the band can be stretched.

The full terms are in our returns, exchanges & repairs policy. If you are unsure, book a 15-minute sizing call and we will help you measure.