Cycling Power Calculator
Estimate power output from speed, weight and grade.
Enter your values
Enter the speed in km/h.
Enter the total rider+bike weight in kg.
Enter the grade in %.
Enter the cda (aero drag area) in m².
Results update instantly as you type — no submit needed. Your values are remembered on this device, and the shareable link reopens the calculator with exactly these numbers.
- Required power
- 146 W
- W/kg
- 1.83
- Speed
- 30 km/h
Quick answer
Cycling power output rises with speed, incline and rider+bike weight due to gravity, rolling resistance and aerodynamic drag.
P = (Crr x m x g + 0.5 x CdA x rho x v^2 + m x g x grade) x v
At a glance
| What it does | Estimate power output from speed, weight and grade. |
|---|---|
| Category | Fitness |
| Inputs needed | Speed, Total rider+bike weight, Grade, CdA (aero drag area) |
| Main output | Required power |
| Formula | P = (Crr x m x g + 0.5 x CdA x rho x v^2 + m x g x grade) x v |
| Cost | Free — no sign-up, no download |
How to use the Cycling Power Calculator
- 1Enter target speed, total weight (bike + rider) and road grade.
- 2CdA of 0.30-0.35 is typical for an upright road position; lower values mean more aerodynamic.
- 3This models steady-state riding; wind and drafting will shift real-world power needs.
Inputs explained
- Speed(km/h)
- Enter the speed in km/h.
- Total rider+bike weight(kg)
- Enter the total rider+bike weight in kg.
- Grade(%)
- Enter the grade in %.
- CdA (aero drag area)(m²)
- Enter the cda (aero drag area) in m².
Worked example
Using the values the calculator loads with:
Inputs
- Speed30 km/h
- Total rider+bike weight80 kg
- Grade0 %
- CdA (aero drag area)0.32 m²
Results
- Required power146 W
- W/kg1.83
- Speed30 km/h
Frequently asked questions
What's a good W/kg?
Recreational riders sustain 2-3 W/kg; elite racers can exceed 5-6 W/kg for an hour.
Why does small speed change need big power?
Aerodynamic drag rises with the cube of speed, so going faster gets disproportionately harder.
What do I need to enter into the Cycling Power Calculator?
Just 4 values: speed, total rider+bike weight, grade, cda (aero drag area). Every field starts with a realistic example, so you can change one number at a time and watch the result update instantly.
How does the Cycling Power Calculator work out the answer?
Cycling power output rises with speed, incline and rider+bike weight due to gravity, rolling resistance and aerodynamic drag. It applies the formula P = (Crr x m x g + 0.5 x CdA x rho x v^2 + m x g x grade) x v and shows the working so you can check each step by hand.
Is the Cycling Power Calculator free, and do I need an account?
It is completely free with no sign-up, no download and no usage limit. Everything is calculated in your browser, so the numbers you type never leave your device.
Results are estimates for general information. For medical, legal, structural or financial decisions, confirm with a qualified professional.