Your Everion is attached to your upper arm with an armband. The device currently comes with an armband that is available in eight different sizes. A precise fit is required to guarantee valid measurements. To find the best size for you, circle the middle of your upper arm with the provided measuring tape with the arm flexed as shown in the picture above. Failing that, use a shoelace or even a smartphone charging cable and place either of these along a flat ruler to determine your arm circumference. Reference the circumferences below to determine the best size for your upper arm.
| Flexed arm circumference (cm) | Band size |
| 19.0 - 21.5 | XXS |
| 22.0 - 24.5 | XS |
| 25.0 - 27.5 | S |
| 28.0 - 30.5 | M |
| 31.0 - 33.5 | L |
| 34.0 - 36.5 | XL |
| 37.0 - 39.5 | XXL |
| 40.0 - 42.5 | XXXL |
If you feel the band size you initially chose is too tight or too loose, please choose the next bigger or smaller band size until it feels comfortable. But be aware that the armband will stretch out over time for a bit.