How to know my Circular Ring size?

Please read our sizing page

The Circular ring sizes use the standard US ring sizes scale.

If the size does not fit when you receive your ring, you'll have 14 days upon delivery to change it for free (except shipping) if your ring is unworn and intact.

The ring comes in 9 different sizes from US 6 to US 14. We don't do half sizes. Circular Ring sizes run about one-half size above standard ring sizes. For example, if you normally wear a standard size 9, we recommend choosing a size 10 for the best comfort.

We offer different options to find your size, from the most accurate to the least accurate method.

1. The most accurate way to find your size is with our Sizing Kit. This kit includes a full set of plastic rings in every size, so you can try them on at home before receiving your actual Circular Ring.

The kit costs $5, and you can order yours separately here or directly with your ring.

2. If you have access to a 3D printer, you can print your sizing rings here.

3. Comparison of Circular size against other smart rings:

• Circular ring 2 size = "Oura Gen 3" & "Oura Gen 4" size
• Circular ring 2 size = Samsung galaxy" size
• Circular ring 2 size = "Ringconn 2" size + 1 (e.g., size 6 Circular = size 7 Ringconn)
• Circular ring 2 size + 1 = "Ultrahuman Air" ring size (e.g., size 7 Circular = size 6 Ultrahuman)

Size 6 = 16.90 mm diameter

Size 7 = 17.70 mm diameter

Size 8 = 18.50 mm diameter

Size 9 = 19.30 mm diameter

Size 10 = 20.10 mm diameter

Size 11 = 20.90 mm diameter

Size 12 = 21.70 mm diameter

Size 13 = 22.50 mm diameter

Size 14 = 23.30 mm diameter

4. An easy-to-use digital sizing tool to help you find the right fit for your smartphone.

Click here if you're on Mobile.

Scan this QR code with your Mobile if you're on a computer.

You will find 3 options:

1. AI-based Photo Sizing with a reference: Take a picture of your hand with a reference card.
2. Ring Comparison: Place a ring you already own on screen to match with Circular’s size guide.
3. Size Conversion Guide: Use our mm Guide for equivalency.

Make sure to meet these requirements for the picture:

✔️ Good lighting

✔️ Plain background

✔️ Spread fingers

✔️ No rings

✔️ Follow the example image closely in terms of hand-phone distance

NOTE: Make sure to get __multiple __measurements with the same results.

NOTE: If you’re unsure of the accuracy you can visit any local jeweler to find your US equivalent finger size. The Circular Ring will match it exactly.

Here is the free Circular sizing guide to be printed

Here is the free Circular rings to be 3D printed

Updated on: 29/10/2025