Cycling Watts Calculator is a focused set of tools for cycling power, FTP, watts per kilogram, speed and climbing performance — nothing else.
Our physics-based calculators (Cycling Watts, Speed, Hill Climb, CdA) share the same cycling power model — gravity, aerodynamic drag, rolling resistance and drivetrain loss — so a result on one stays consistent with the others; the CdA Calculator solves that same model algebraically in reverse, from measured power and speed. Training and performance calculators (FTP, Power Zones, W/kg, Critical Power, VAM) each use their own documented, cycling-specific formulas and conventions instead — Andrew Coggan's published training-load model for FTP and power zones, and the Monod & Scherrer two-parameter model for Critical Power, among others.
This keeps related calculations consistent while allowing each calculator to use the model appropriate to its purpose.
Every formula and default constant used on this site is documented, with its source and assumptions, in the project's formula reference. Nothing is invented to fill a gap — where a value depends on an assumption (air density, tire rolling resistance, drivetrain efficiency), that assumption is stated rather than presented as universally exact.
Every result on this site is an estimate for training and planning purposes — not a laboratory measurement. Real-world power output can differ because of equipment, road surface, wind variability, rider position, and day-to-day physiological variation. Treat these numbers as a consistent way to compare scenarios, not as a substitute for a calibrated power meter.
