Cycling Power Estimator
Estimate watts needed to hold a given speed at your weight and road gradient.
100% client-side · no upload
Estimated Power
Watts per kg
How to use
- Enter combined rider and bike weight in kilograms.
- Enter the target speed in km/h and road gradient in percent (negative for downhill).
- Results update instantly — see estimated watts and watts per kilogram.
Related tools
- Running Pace Calculator — pace and speed conversion
- Training Load Calculator — RPE × duration session stress
- VO₂ Max Estimator — aerobic capacity from heart rate
- Heart Rate Zones — training zones from max HR
More ways to use this tool
Frequently Asked Questions
- Is this cycling power calculator free?
- Yes, completely free with no signup and no usage limits.
- Does my data leave my device?
- No. All calculations run in JavaScript inside your browser. Nothing is sent to any server.
- Does it work on mobile?
- Yes. The calculator is mobile-first and works on iPhone Safari and Android Chrome.
- What constants does the model use?
- Rolling resistance coefficient (Crr) 0.004, drag area (CdA) 0.4 m², and air density (ρ) 1.225 kg/m³ — typical values for a road cyclist in a standard position.
- Can I use negative gradients for downhill?
- Yes. Enter a negative percentage. At high speeds on steep descents the total power may reach zero because aerodynamic drag balances gravity.
Last updated: By jarvisbox