As treadmill manufacturers are aware of the length of their running belt and the speed at which it is moving, distance-trackers on these machines should be able to provide a good level of accuracy.
“It likely depends on the treadmill, but (in general) they are quite accurate,” says Grover, adding: “Keep in mind that they will certainly feel different than running outside or on a track. Treadmills usually impact things such as length of stride and consistency of terrain.”