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ringsizerchart

Smart ring size chart

Smart rings are not sized like jewellery: Oura, Samsung and Ultrahuman all say to use their sizing kits. Oura Ring 4 comes in 4 to 15, the Galaxy Ring 5 to 15 and Ultrahuman Ring AIR 5 to 14, all in whole sizes. Measure your jewellery size here first to know which kit sizes to try.

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 918.95 mm · 0.746" inside · 59.5 mm round
Inside diameter18.95 mm
Band wall2.6 mm
Jump to US

Full chart 16 rows

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

Smart ring sizes by maker

4 rows
Download CSV
Smart ring size ranges for Oura Ring 4, Oura Ring Gen 3, Samsung Galaxy Ring and Ultrahuman Ring AIR, with half sizes, interior and sizing kit
Oura Ring 44–15NoSmooth titanium inside; sensors recessed to 0.3 mmRing 4 sizing kit (not shared with Gen 3)
Oura Ring Gen 36–13NoEpoxy inside with sensor bumps about 1.3 mm highGen 3 sizing kit
Galaxy Ring5–15NoThree raised sensor bumps; wear them toward the palm11-ring sizing kit, worn for 24 hours
Ring AIR5–14NoTitanium shell; maker says sizes differ from jewellery sizes10-ring sizing kit, worn for two nights

Your jewellery size as a smart-ring baseline

12 rows
Download CSV
US ring sizes 4 to 15 with inside diameter and which smart-ring sizing kits include that number
Actions
14.88has 4———
15.69has 5—has 5has 5
16.51has 6has 6has 6has 6
17.32has 7has 7has 7has 7
18.13has 8has 8has 8has 8
18.95has 9has 9has 9has 9
19.76has 10has 10has 10has 10
20.57has 11has 11has 11has 11
21.38has 12has 12has 12has 12
22.20has 13has 13has 13has 13
23.01has 14—has 14has 14
23.82has 15—has 15—

05 / Field guide

Measure first,
then the kit.

Smart rings put sensors on the inside of the band, so they are thicker than jewellery and some have bumps that press on the finger. All three big makers say their sizes do not match ordinary ring sizes and send a free or cheap sizing kit. Your jewellery size is still the right place to start, because it tells you which kit rings to try first.

The three main rings

Oura Ring 4 comes in whole sizes 4 to 15. Its sensors are recessed to about 0.3 mm in a smooth titanium inside, where the older Gen 3 had bumps about 1.3 mm high. The Ring 4 kit is not shared with Gen 3, and a size in one may not fit the same in the other.

Samsung’s Galaxy Ring comes in sizes 5 to 15 with three raised sensor bumps; Samsung says to wear them toward the palm. Its kit has 11 sample rings and asks you to wear one for 24 hours, including sleep. Ultrahuman’s Ring AIR comes in sizes 5 to 14, again without half sizes, and its kit asks for two nights’ wear.

Why sizing is different

A sensor ring has to sit still: if it spins, the light sensors lose contact and readings get noisy. That pushes the right fit toward snug. Bumps take up space on the inside, and the bands are 7 to 8 mm wide, which on its own would suggest going up half a size. The two effects pull in opposite directions, which is why makers rely on kits rather than conversions.

Wear the sample ring on the finger you plan to use (makers suggest index, middle or ring finger), through a day and a night. It should slide over the knuckle with a little resistance and not turn on its own.

How to use this page

Measure a jewellery ring that fits the target finger with the 1:1 circle, then look up that number in the smart-ring table. If your jewellery size is 9, ask for a kit or start with sizes 9 and 10 of the brand’s samples, since a wide band usually needs more room. Treat the result as a baseline, never as an order size.

We do not publish a conversion like “Oura 10 = US 9½”, because no maker publishes one and any table you find online is a guess.

Questions

Answered plainly.

01Is Oura ring sizing the same as normal ring sizes?+

No. Oura says its sizes differ slightly from standard sizes and asks buyers to use the Oura Ring 4 sizing kit, which runs 4 to 15 without half sizes.

02What sizes does the Samsung Galaxy Ring come in?+

Sizes 5 to 15. Samsung says your usual ring size may not be the best fit because of the sensors and recommends wearing a kit ring for 24 hours.

03Should I size up for a smart ring?+

Often, because smart rings are 7–8 mm wide, but the sensor fit should be snug. Start with your jewellery size and the next size up from the maker’s kit.

04Do Oura Ring 4 and Gen 3 fit the same?+

Not necessarily. Gen 3 had 1.3 mm sensor bumps and an epoxy inside; Ring 4 has a smooth titanium inside. Oura’s Ring 4 kit is specific to Ring 4.

05Which finger should a smart ring go on?+

Makers suggest the index, middle or ring finger. Size the finger you will actually wear it on, since fingers differ by one or two sizes.

06Can I use this site instead of a sizing kit?+

Use it to find your jewellery size and choose which kit sizes to try. Makers do not publish conversions, so the kit is the final check.

Ring sizesUS · inside Ø mm

Carat sizes

Necklace lengths