Speed display inaccurate

Hi, fairly new to Zwift and have managed to set everything up OK. I’m about 4 rides in and have noticed that my speed and distance is some way off what I would expect and also what my smart watch is tracking. (about 3 mph difference between watch and Zwift display. I understand from these forums that Zwift will never be entirely accurate, especially with a dumb/basic trainer and I’m content with that. Just keen to understand why such a difference between watch and Zwift and if there’s any simple steps I may have missed during setup or first workout? Any tips appreciated. Thanks

Hi @Alex_O_Donnell_NTC

Welcome to the Zwift Forum.

Your cycling computer and Zwift won’t match. Your cycling computer only knows the wheel speed it doesn’t know if you are going up or down.

You wheel speed determine your power and Zwift calculate speed from power taking your weight hight and road profile into account.