Fit decides signal quality more than anything else you do. The Circular Ring is available in 9 sizes, from US 6 to US 14 (no half sizes). Circular sizes run about one-half size above standard ring sizes — if you normally wear a standard size 9, choose a size 10 for the best comfort.
Most people use the digital tool. The sizing kit is the most reliable, and the one we recommend if you are between sizes.
Measure your fingers in a few steps from your smartphone. Two methods: compare a ring you already own, or take photos so AI can estimate your size.
Most popular Order with a sizing kitOn the ring's page, choose Sizing kit as your size. For an extra $5 you receive a physical kit with every size, then confirm your choice before the ring ships.
Most reliable Print your own at homeHave a 3D printer? You can print your own sizing rings at home.
FreeAny local jeweller can give you your US equivalent finger size. Then choose about half a size above it — a standard 9 means a Circular 10.
No app neededYou can place an order with a sizing kit but you can also avoid that by using our easy-to-use digital sizing tool to help you find the right fit with your smartphone. You'll find 3 options:
On mobile: tap here to use the digital sizing tool.
On computer: scan the code with your phone — the tool needs a camera.
Take a picture of your hand with a reference card. Good lighting, plain background, spread fingers, no rings, and follow the example image closely in terms of hand-phone distance.
Make sure to do multiple measurements with the same results. If you're unsure of the accuracy you can visit any local jeweller to find your US equivalent finger size, then choose about half a size above it — a standard 9 means a Circular 10.
Place a ring you already own on screen to match with Circular's size guide.
Use our mm guide for equivalency.
Small things that change the reading. Worth two minutes before you order.
👉 Choose the larger size of both but make sure it's snug enough not to fall off.
👉 If you have large knuckles, choose the smallest size that slides over them comfortably.
| Other ring | How Circular compares |
|---|---|
| Oura Ring Gen 3 & 4 | Same size as the Circular Ring |
| Samsung ring | Same size as the Circular Ring |
| RingConn 2 | Circular size = RingConn size + 1 (e.g. size 6 Circular = size 7 RingConn) |
| Ultrahuman Air | Circular size + 1 = Ultrahuman size (e.g. size 7 Circular = size 6 Ultrahuman) |
On the ring's product page, choose Sizing kit as your size. For an extra $5 you will receive a physical kit containing all Circular ring sizes. Try them on and once you have chosen your size, come back to your order status page link to confirm it. You will then be shipped your Circular ring. This is the most reliable sizing method. Please look out for a separate email called "Confirm your Circular ring size for order" (check your spam) from contact@circular.xyz, and click the "Validate my size" button to edit your size.
No worries. You have 14 days after delivery to request a size exchange, as long as the ring is unworn and intact. Return shipping is not included. See warranty and returns.
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