Climb time calculator
How long will it take you to get to the top? At 200 W and 165 lb (75 kg), a 3.1 mile climb at 6% takes about 24 minutes at 7.8 mph. Enter your numbers, with power prefilled from your profile at 90% of FTP, and get time, average speed, VAM and calories burned.
Don't know your power? Take a test in the FTP calculator and save the result to your profile: this field then fills itself with 90% of FTP, a typical pace for a longer climb.
Assumptions: hands on the hoods (CdA 0.32 m²), rolling resistance 0.005, air density 1.19 kg/m³, drivetrain efficiency 97.5%, no wind. Real times can differ by a few percent.
How is climbing time calculated?
Underneath sits the classic cycling power equation, the same one used to model race performances:
P = M x g x v x (sin a + Crr x cos a) + 0.5 x rho x CdA x v^3 P - power at the pedals [W] M - rider plus bike mass [kg] g - gravity, 9.81 m/s^2 a - road angle (from the gradient in percent) Crr - rolling resistance, assumed 0.005 rho - air density, assumed 1.19 kg/m^3 CdA - drag area, 0.32 m^2 (hands on the hoods) v - the speed we are solving for [m/s]
Drivetrain efficiency of 97.5% is applied on top, since the chain and derailleurs eat about 2.5% of your power. The equation cannot be inverted with a simple formula, so speed is found numerically by bisection: the calculator tries speeds until required power matches the power you entered. Time is climb length divided by that speed, VAM is elevation gain divided by time in hours, and calories come from the kJ ≈ kcal shortcut (roughly 24% muscular efficiency cancelling the unit conversion).
Worked example: a 165 lb (75 kg) rider on a 20 lb bike, 3.1 miles at 6% (984 ft of climbing), holding 200 W. The model gives 7.8 mph, 23 min 50 s, a VAM of about 755 m/h and 286 kcal. Drop 22 lb from the rider and the same 200 W gets to the top more than two minutes sooner: on a climb, weight is half the equation.
What power should you enter?
For a climb lasting more than about fifteen minutes, 85-95% of FTP is realistic, and this calculator suggests 90% of the FTP saved in your profile. On short ramps of a few minutes you can hold more than FTP; on a climb in the middle of a long day, 70-80% is wiser, because the legs still have to get home. If you do not know your FTP yet, the FTP calculator turns a test result into one, and the GPX route difficulty tool applies the same physics to a whole route file rather than a single climb.
Frequently asked questions
- What determines how long a climb takes?
- Above about 5% gradient, more than three quarters of your power goes into fighting gravity, so two things dominate: your power-to-weight ratio in W/kg and the length of the climb. Aerodynamic drag, which rules on the flat, matters little at 6-8 mph. That is why a lighter rider at the same absolute power gets to the top first.
- What is VAM in cycling?
- VAM (velocità ascensionale media) is average climbing speed expressed as vertical metres gained per hour. Coach Michele Ferrari popularised it, and Strava and head units display it today. As a rough scale: 800-1,000 m/h is a solid amateur pace, 1,500 m/h is a strong racer, and the front of the Tour de France exceeds 1,700-1,800 m/h on decisive climbs. VAM is most meaningful on climbs above 7% lasting 20 minutes or more.
- How many calories does a climb burn?
- Calories follow power and time, not gradient: at 200 W every hour of riding is about 720 kcal. A 3.1 mile climb at 6% at 200 W takes just under half an hour, so roughly 280-290 kcal. The gradient changes how long you are out there, not the rate at which you burn energy.
- Why does the real time differ from the calculation?
- The model assumes constant power, no wind and an even gradient. In reality the gradient undulates, wind can add or remove ten percent or more, and the surface may be worse than assumed. Treat the output as a solid forecast accurate to within a few percent, not a stopwatch.
- Is this accurate for e-bikes or heavy touring setups?
- Yes, as long as you enter the real total weight and the power actually reaching the pedals or wheel. For a loaded tourer, add the luggage to the bike weight. For an e-bike, add the motor's sustained output to your own and be aware that most systems cut assistance around 15.5 mph (25 km/h), which rarely matters on a climb.