FTP calculator
Turn a 20-minute, 8-minute or ramp test into a functional threshold power number, with your seven training zones.
Power zone calculator
Split your FTP into the seven Coggan training zones, from active recovery to neuromuscular sprints.
Watts per kg calculator
Divide your FTP by your weight to get the number that decides how fast you climb, plus where it places you.
Heart rate zone calculator
Five training zones from your maximum heart rate, matching the model WattLog.PRO uses on recorded rides.
Calorie calculator
Convert average power and ride time into calories burned - the one estimate that is genuinely accurate.
TSS calculator
Turn normalised power, FTP and duration into a training stress score and intensity factor for the session.
Power to speed calculator
Work out the watts needed for a given speed, or the speed a given power will produce, on any gradient.
Gear ratio calculator
See the speed, ratio, gear inches and development for any chainring and sprocket combination.
Stop typing numbers in by hand WattLog.PRO records your trainer, power meter and heart rate monitor live, then computes all of this from the ride itself. Guest mode needs no account.
Open WattLog.PROWhy these eight
Every calculator here answers a question a cyclist actually asks mid-season: what is my threshold, what should this interval feel like, how hard was yesterday, what gear will I need on that climb. They share one set of constants, so the zones you see here are the zones WattLog.PRO uses when it records your ride.
That consistency matters more than it sounds. Most online calculators disagree with each other because they quietly use different zone models - a Z3 on one site is a Z2 on another. Everything on this page uses the same 7-zone Coggan power model and the same 5-zone percentage-of-maximum heart rate model that the app applies to your recorded data.