# How is power calculated? Every app gives me wildly different results

**URL:** <https://forums.zwift.com/t/how-is-power-calculated-every-app-gives-me-wildly-different-results/602448>\
**Category:** Bugs and Support\
**Created:** [February 16, 2023, 6:48pm UTC](https://forums.zwift.com/t/how-is-power-calculated-every-app-gives-me-wildly-different-results/602448 "2023-02-16T18:48:29Z")\
**Posts on this page:** 1\
**Showing post:** 5

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**Author:** ![Gerrie\_Delport\_ODZ](https://sea2.discourse-cdn.com/gozwift/user_avatar/forums.zwift.com/gerrie_delport_odz/32/437556_2.png) [@Gerrie\_Delport\_ODZ](https://forums.zwift.com/u/Gerrie_Delport_ODZ)\
**Post date:** [February 16, 2023, 7:25pm UTC](https://forums.zwift.com/t/how-is-power-calculated-every-app-gives-me-wildly-different-results/602448/5 "2023-02-16T19:25:49Z")

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This should be helpfull.

It all depend on what power-speed curve the software is using.

> [@How Does Zwift Determine My Speed?](https://forums.zwift.com/t/how-does-zwift-determine-my-speed/427729):
>
> How Does Zwift Determine My Speed? For Wheel-on Classic Trainers: Zwift takes the wheel speed broadcast by your speed sensor and the power curve (see example below) of the trainer you select on the Pairing Screen and converts that to virtual watts, also known as “zPower”. Your in-game speed is de…

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