Cycling Power Calculator
Estimate the watts you need to hold your target speed across gradients with a transparent gravity + aerodynamic drag model.
Cyclist & terrain details
How to use this calculator
Enter your total mass (cyclist + bike) and the speed you plan to sustain. Add the route gradient to see how the gravitational load changes the watts required. Hit Calculate or rely on the debounced updates that fire after you pause typing.
The calculator keeps everything in metric units for clarity. Use the Reset button to restore the default traveler (70 kg at 20 km/h on a 5% incline) whenever you need a baseline.
Methodology
The model adds two well-established contributors: the gravitational work needed to lift the mass up the incline, and the aerodynamic drag that scales with the cube of speed. Gravity uses the familiar g=9.81 m/s² constant, while aerodynamic drag multiplies air density, a drag coefficient, and frontal area before scaling with the velocity cube (speed converted to m/s).
Results show the total power plus the split between gravity and drag so you can see which factor dominates. The computation runs on the values you provide; it never shows NaN or Infinity because we validate every number and keep the UI stable.
Data source
This calculator follows the established cycling power formulas highlighted by professional sports science resources, ensuring the physics mirrors how coaches and engineers model effort. See the references in the Citations section for the exact source used in the audit.
Glossary of terms
- Weight: Combined weight of rider, kit, and bicycle.
- Speed: Target speed in kilometers per hour.
- Gradient: Incline percentage of the course.
- Power: The total watts a rider must sustain to overcome gravity and aerodynamic drag.
How it works: step-by-step example
A 70 kg rider who maintains 20 km/h on a 5% climb needs to cover gravitational work first, then add the drag losses. Plugging these values into the calculator breaks the effort into two components and sums them to produce the power required to maintain the speed.
Frequently asked questions
What is cycling power?
Cycling power is the rate at which the body turns chemical energy into mechanical work on the bike, measured in watts.
Why is knowing cycling power important?
Power helps cyclists manage training load, pace a climb, and compare performance inside and outside the saddle.
How accurate are these calculations?
The numbers are theoretical; real-world losses from wind, road surface, and rider position can nudge the true watts required.
Can this calculator be used for mountain biking?
Yes, though mountain terrain adds technical losses that this simplified model does not capture, so treat the output as a starting point.
Is this tool suitable for professional cyclists?
Absolutely. Pros use similar back-of-the-envelope physics to verify power targets before refining them with wind-tunnel data.