How to Find Your Perfect Ultrahuman Ring Size

Finding the right fit now will ensure your ring is comfortable, giving you the most accurate data when you start using it. 

Step 1 : Start with a Sizing Kit

The Ultrahuman Ring comes in whole sizes only — so getting the right fit is crucial. We recommend trying the Sizing Kit for at least 2 nights before placing your order.

Because your finger size isn't constant. Fingers tend to swell in the morning and after exercise, then shrink in cooler temperatures. Sleeping with the sizing ring helps you confirm that your chosen size won't feel too loose or too tight while you rest.

Sensor position: The sizing ring has a marked line that simulates the sensor placement on the inner band. Always rotate this mark to face the palm side of your finger — this mimics how the real ring sits during use.

Step 2: Choose the Right Finger

Ultrahuman recommends wearing the ring on your index finger first, as it provides the most accurate sensor readings. If that's not comfortable, the middle or ring finger work just as well.

Avoid the pinky and thumb. The bone structure and skin surface on these fingers make it harder for the sensor to maintain consistent contact, which can affect data accuracy.

Step 3: Check the Fit — Not Too Tight, Not Too Loose

Use these 4 checks to confirm your size is right:

• Snug fit: The ring shouldn't spin freely on your finger. The PPG sensor (the green/red light on the inner band) needs consistent skin contact to work accurately.
• Passes over the knuckle: When removing the ring, you should feel slight resistance at the knuckle — but you shouldn't need soap to get it off.
• Fist test: Make a fist. If you see a large gap between the ring and the top of your finger, the ring is likely too loose.
• Best time to measure: Measure your finger size in the evening, when fingers are at their most swollen.

Tip : Weather affects finger size — fingers shrink in the cold and swell in the heat. If you're between two sizes, always go with the larger one.

**Sizing Kits are non-refundable and cannot be exchanged.