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Ascent Time Calculator — Estimate Climbing Time
Estimate climbing time from power, weight and gradient.
How We Calculate This
Ascent Time Estimation
Based on the Martin et al. (1998) road-cycling power model, the calculator solves for the steady-state speed at which your power output balances the forces resisting the climb:
- P × η = P_gravity + P_rolling + P_aero, where η ≈ 0.976 is the drivetrain efficiency (a clean chain loses ~2.4% before the wheel)
- P_gravity = m · g · gradient · v (the dominant term on a climb)
- P_rolling = Crr · m · g · v
- P_aero = ½ · ρ · CdA · v³ (small at low climbing speeds)
- Time = Distance / Speed
- VAM = Elevation Gain / Time (in hours) — vertical metres climbed per hour
Frequently Asked Questions
It is accurate for steady-state climbing in still air. Wind, variable gradient, fatigue and road surface will all affect actual times. Expect real times to be 5-15% slower.
Use the power you can sustain for the expected duration. For climbs under 20 minutes, use about 105% of FTP. For 30-60 minute climbs, use FTP. For longer, use 85-95% of FTP.
No, this calculates time for a continuous ascent. For routes with mixed terrain, break them into segments or use the Ride Time Calculator.
Related Calculators
Climbing Category Calculator
Classify a climb by its category based on length and gradient.
Route Gradient Calculator
Calculate gradient percentage from elevation and distance data.
Elevation Gain Calculator
Calculate total elevation gain from gradient and distance.
Descent Speed Calculator
Estimate safe descent speed based on gradient and conditions.
Route Difficulty Calculator
Rate route difficulty from distance, elevation and gradient data.
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Last updated: February 2026
All calculations are estimates. Always verify results and consult a professional bike fitter where appropriate.