Cycling Power Estimate
Rough watts from speed, mass, and grade.
Inputs
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Formula
P = v × (mg sinθ + Crr mg cosθ + ½ρ CdA v²)
Physics-based estimate: gravity on slope, rolling resistance, and aerodynamic drag with default CdA=0.5 m².
Worked example
75 kg total at 25 km/h on 3% grade might need ~200 W depending on wind — check headline.
Where this can give the wrong answer
- Wind and drafting ignored.
- CdA varies by position — drops on drops.
- Indoor trainers differ from road.
FAQ
- Sustained FTP should be below short peak estimates from short climbs.