Cycling Power Calculator
Estimate the power in watts needed to hold a given cycling speed. The model adds rolling resistance, aerodynamic drag and the climbing power for any gradient.
How to estimate cycling power
- Enter your speed, body weight and bike weight.
- Set the gradient and, if you wish, the rolling and drag coefficients.
- Read the total watts and how they split across the three forces.
Examples
30 km/h on the flat
30 km/h, 75 kg rider, 8 kg bike, 0% grade
About 176 watts: 142 W air, 34 W rolling, 0 W climbing
Frequently asked questions
How is cycling power estimated?
It sums three forces: rolling resistance, aerodynamic drag and the power to climb. Each is multiplied by speed to give watts at the wheel.
Why does air drag dominate at speed?
Aerodynamic power rises with the cube of speed, so it grows fast. On the flat at road speeds, most of your power fights the air.
What CdA and Crr should I use?
Defaults are a CdA of 0.4 and a Crr of 0.005, typical for a road rider on the hoods. Lower the CdA for an aero position or aero gear.
Does this include drivetrain losses?
No. It reports power at the wheel with an assumed drivetrain efficiency of 1.0. Real pedal power is a few percent higher.
How much does a climb add?
A lot. At 30 km/h, a 5 percent grade adds roughly 340 watts of climbing power on top of the flat-road figure.
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