⚡ Cycling Power Calculator
Enter ride conditions to estimate required watts and watts per kilogram for a given speed.
Typical road position ranges 0.25–0.35 m²; aero TT 0.20–0.25 m².
Race tyres ≈ 0.003–0.005, gravel tyres ≈ 0.006–0.010.
Positive = headwind, negative = tailwind.
Total Power
385 W
Watts per kg
5.34 W/kg
Gravity & Rolling
157 W (climb) + 31 W (rolling)
Aerodynamic Drag
196 W
How to Use This Calculator
Input weight
Include rider + bike to capture climbing and rolling resistance loads.
Set course conditions
Enter target speed, gradient, and wind scenario.
Adjust aero & rolling
Use CdA/Crr values from fit sessions or published tyre data.
Review power demand
Compare to your FTP or training zones to judge feasibility.
Formula
P = m·g·v·sinθ + m·g·Crr·v + ½·ρ·CdA·v3
Total power equals the sum of climbing (gravity), rolling resistance, and aerodynamic drag components. This model assumes steady-state riding and does not include drivetrain losses (~2–3%).
Example
80 kg system mass at 40 km/h on flat road, CdA 0.32, Crr 0.004 → ~295 W total (230 W aero, 63 W rolling).
Variables
- m: Total mass (rider + bike)
- v: Velocity (m/s) adjusted for wind
- Crr: Rolling resistance coefficient
- CdA: Aerodynamic drag area
Power Planning Tips
Use power estimations to pace climbs, plan time trials, or gauge gains from aero equipment. Remember that crosswinds and drafting can dramatically alter actual power demands.
Improve Efficiency
- Lower CdA via aero position, tighter clothing, and aero wheels.
- Reduce Crr with quality tyres and proper inflation.
- Lighten bike and kit for climbing-dominant routes.
Use Cases
- Time trial pacing: ensure target speed aligns with sustainable watts.
- Triathlon planning: balance power output with run energy demands.
- Equipment choices: quantify watt savings from aero helmets or skinsuits.
Frequently Asked Questions
Does drafting reduce required watts?
Yes. Drafting lowers effective CdA drastically. This calculator assumes solo riding; reduce CdA for bunch situations.
How accurate is the model?
It’s a first-principles estimate. Field power meters provide real-world validation—use both for precise pacing.
What about acceleration?
Accelerations require extra kinetic energy not included here. For steady pacing, the model works well.
Should I include drivetrain losses?
You can. Multiply total power by 1.03 for a 3% drivetrain penalty if you want to match crank-based readings.
Can I change air density?
Currently fixed to sea-level conditions. Future updates may add temperature/altitude inputs.