Cycling Power Output Calculator

Work out cycling power output instantly with clear inputs, formula shown and shareable results.

About Cycling Power Output Calculator

Cycling power splits into aerodynamic drag (rising with the cube of speed), climbing power (weight times gradient times speed) and rolling resistance. On the flat above 25 km/h aerodynamics dominate; on a climb above about 5% gravity dominates and position matters far less.

Formula

Cycling power

P = 0.5 rho CdA v^3 + m g (gradient) v + Crr m g v, all divided by drivetrain efficiency

Worked example

With the default values below, Cycling Power Output Calculator returns Power output of 319. Change any input above and every figure here is recalculated in your browser.

Inputs used

Speed: 32 km/h
Rider and bike weight: 82 kg
Gradient: 2 %
Drag area (CdA): 0.32 m²

Results

Power output: 319 W
Power against air resistance: 138 W
Power against gravity: 143 W
Power to weight: 3.89 W/kg

Step by step

1Values used
2Cycling power
3Power output= 319 W
4Power against air resistance= 138 W
5Power against gravity= 143 W
6Power to weight= 3.89 W/kg

Assumptions and limits

The result is derived only from the 4 inputs listed above. Anything not among them is not part of the calculation.
In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
Figures are rounded for display to 2 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.

How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.

Frequently Asked Questions

Why does position matter more on the flat?

Because aero power scales with v cubed and is the largest term at speed. On a steep climb speed is low, so drag is small and weight dominates.

What CdA values are typical?

0.40 m2 upright on the hoods, 0.30-0.32 in the drops, 0.25 in a good time trial position and under 0.20 for elite TT riders.