Cycling Power Calculator
Estimate cycling power output in watts based on speed, rider weight, and gradient using simplified aerodynamic and gravitational models.
mph
lbs
%
Estimated Power
123 W
Power-to-Weight1.47 W/kg
Aerodynamic Drag90 W
Climbing Power0 W
Estimated Power vs Speed
How Cycling Power Is Estimated
Power required to cycle comes from three main sources: aerodynamic drag, rolling resistance, and gravity.
Formula
Total Power = P_aero + P_rolling + P_gravity
Where v is speed in m/s, g is 9.81 m/s^2.
Key Insight
Aerodynamic drag increases with the cube of speed, so doubling your speed requires roughly 8 times the power to overcome air resistance.
Example Calculation
Riding at 18 mph on flat road, 185 lbs total rider+bike weight.
- 01Speed = 18 * 0.44704 = 8.05 m/s
- 02Mass = 185 * 0.4536 = 83.9 kg
- 03P_aero = 0.5 * 1.225 * 0.2816 * 8.05^3 = 90.0 W
- 04P_rolling = 0.005 * 83.9 * 9.81 * 8.05 = 33.1 W
- 05P_gravity = 0 (flat road)
- 06Total = 90 + 33 + 0 = 123 W
- 07W/kg = 123 / 83.9 = 1.47 W/kg
Frequently Asked Questions
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