Stryd is designed to be accurate out of the box and often does not require calibration. There is some variability across devices and runners. It is possible to fine-tune the accuracy of Stryd.
1. You must compare the distance measured by Stryd with a known distance. We recommend you head to the track and measure it with a measuring wheel as even certified tracks can be off by up to 1%.
2. After you have tested your Stryd, the next step depends on your device:
Most Garmin, COROS and Polar watches allow you to set a calibration factor.
The Stryd app on the Apple Watch allows you to set a calibration factor by going into settings. The math: (Actual Distance/Stryd Distance)
Suunto watches do not allow setting a manual calibration. You can try to look for an open road that is straight and long enough to run about 15 minutes. Suunto can auto-calibrate Stryd, but you will be relying on the Suunto GPS. After calibration, your Stryd will be accurate in places where GPS is less reliable such as wooded areas and around high-rise buildings.