Enter your power, your weight and the gradient to see how long a climb will take, how fast you will go and what VAM you will climb at.
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Elevation gain: 1106 ft
VAM (vertical ascent per hour) is a standard climbing-performance metric independent of unit system. Assumes a typical road setup at sea level with no wind. For full control over aerodynamics and elevation, use the advanced power model.
Completed a climb already? Calculate your actual VAM.
Climbing speed is driven by power-to-weight, so the quickest way to size up a hill is by W/kg. This table is for a 70 kg rider on an 8 kg bike climbing 5 km at 6% (300 m of gain), hands on the hoods, at sea level in still air:
| Sustained W/kg | Watts | Speed | Time | VAM |
|---|---|---|---|---|
| 2.5 | 175 W | 11.9 km/h | 25:08 | 715 m/h |
| 3 | 210 W | 14.1 km/h | 21:18 | 843 m/h |
| 3.5 | 245 W | 16.1 km/h | 18:36 | 966 m/h |
| 4 | 280 W | 18.1 km/h | 16:36 | 1083 m/h |
| 4.5 | 315 W | 19.9 km/h | 15:03 | 1194 m/h |
| 5 | 350 W | 21.7 km/h | 13:49 | 1300 m/h |
Every extra half W/kg takes time off, most of all at the lower end of the table. To find where your own W/kg sits, use the W/kg calculator.
A common back-of-envelope shortcut for a hill is that the power to climb is weight × 9.81 × elevation gained ÷ time, plus roughly ten percent for friction and air. It is a fair first guess, and it shows why weight matters so much. The full model is more exact because it counts each force separately. In the reference climb above, gravity accounts for about 86% of the wheel power, air drag about 9% and tire rolling resistance the rest. On steeper or slower climbs gravity's share rises further; on gentle gradients, drag takes a bigger bite and the shortcut underestimates the watts.
The same 4 W/kg effort (280 W for this rider) produces very different results as the road tilts up:
| Gradient | Speed | VAM | Time for 5 km |
|---|---|---|---|
| 3% | 26.6 km/h | 797 m/h | 11:17 |
| 5% | 20.5 km/h | 1022 m/h | 14:40 |
| 7% | 16.1 km/h | 1124 m/h | 18:38 |
| 10% | 11.9 km/h | 1187 m/h | 25:09 |
| 12% | 10.1 km/h | 1206 m/h | 29:38 |
Speed falls steeply while VAM changes much less, which is why climbers quote VAM, since it stays comparable when the gradient changes. To go from a finished climb back to VAM, use the VAM calculator.
Take 5 kg off the rider at unchanged watts and the 4 W/kg, 6% reference climb goes from 16:36 to 15:47, a saving of 48 seconds. The gain is only real if the watts stay the same: weight lost at the cost of power gains nothing. Decisions about body weight are personal and health-related, and beyond what a calculator can advise on.
Many riders start with a target, such as "up this climb in twenty-five minutes", and want the watts. Divide the climb's length by the target time to get a required speed, then enter that speed and the average gradient into the full cycling power calculator in Speed to Watts mode. It reports the watts and the W/kg you would need, which you can compare with your FTP from the FTP calculator to judge whether the target is realistic.
A constant-power calculation assumes you ride evenly. Real climbs have steeper pitches, flatter breathers, and the temptation to surge. Holding steady power usually finishes faster than uneven effort at the same average. Use the result as a pacing target, then adjust for wind, heat and fatigue on the day. For the flat sections of a route, the cycling speed calculator converts the same power into speed.
