Simple Watt/Kg Calc

To use this calculator you will need to know your 5s / 1min / 5min / power numbers and your current FTP. Best place to get these would be from your power curve. Strava has a great one for premium members or services such as Training Peaks or Wattsboard also has them. Wattboard is actually free too. This neat little tool with also work our your Zwift Racing category also.

The figures in this calculator are based on Andy Coggan's power zones. You can see the full list here

maximal power output

What is your current weight?

5 sec

1 min

5 min


Zwift Racing:


w/kg in zwift

In Zwift, you can always see your w/kg by looking at the number right below your name in the Riders list. This number will change as your ride, but should be relatively consistent if you’re putting in an even effort. Zwift also uses w/kg as a means of categorizing group rides and races.

  • A

    4 - 5 w/kg

  • B

    4 - 3.2 w/kg

  • C

    3.1 - 2.5 w/kg

  • D

    2.4 - 1 w/kg

why does w/kg matter?

w/kg matters as an indicator of performance and speed. On a smooth, flat road, cyclists with a greater power number will almost always go faster. But go to the hills or even on undulating roads and w/kg really starts to matter. If we have two cyclists both producing 250 watts, on a flat road, they’ll be about even. But when the road turns to hills, the lighter of the two cyclists will be faster.

want to improve your w/kg?

There are basically just three ways in which you can affect change to w/kg.

  1. Increase your power while keeping your weight constant
  2. Keep your power constant and decrease your weight.
  3. Increase your power while also decreasing your weight.

want to learn more?