Cycling Power (Watts) Calculator
Estimate the watts required to hold a given speed on a given gradient, with a breakdown of where the power goes.
How to use the cycling power calculator
- Enter your total mass (rider + bike + kit).
- Enter your target speed and the gradient.
- Click Calculate to see the power required and its breakdown.
A model, not a measurement
This uses typical road values for drag and rolling resistance. Your real power depends on riding position, road surface, tires and wind, so treat it as a well-informed estimate.
Frequently asked questions
How much power to ride 30 km/h?
On flat ground a typical road rider needs roughly 150–200 watts to hold 30 km/h, depending on position, weight and aerodynamics.
What slows a cyclist down most?
On the flat, air resistance dominates and grows with the cube of speed. On climbs, gravity takes over, which is why power-to-weight matters uphill.
Related tools
Power-to-Weight Calculator
Calculate your watts per kilogram (W/kg) — the number that best predicts climbing and racing performance.
FTP Calculator
Estimate your Functional Threshold Power from a 20-minute test and get your full set of power training zones.
Climbing Time Calculator
Estimate your time up a climb from your power and weight, plus your climbing rate (VAM).