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Free climbing tool

Climb & Gradient
Watts.

Find the watts needed to ride up a hill from your weight, gradient and speed, plus your W/kg, climb time, elevation gained and VAM.

The climb
Power needed
208
watts
Easy Tempo All-out
Power to weight 2.78 W/kg
Climb time 15:00
Elevation gained 633 ft
VAM (climb rate) 771 m/h

Uses rolling resistance 0.005 and an aero drag area of 0.40 for a rider on the hoods. On steep climbs gravity dominates, so these assumptions barely move the result.

The physics

How the calculator works

Climbing power is the sum of three forces you push against, multiplied by your speed. On a hill, one of those forces, gravity, is by far the largest.

g
Gravity = total weight × gravity × the slope. This is the big one on any real climb and rises directly with weight and gradient.
~
Rolling = weight × gravity × tyre rolling resistance. A small, steady drag from your tyres on the road.
air
Aero = half × air density × drag area × speed squared. Tiny at climbing speeds, which is why big riders still struggle uphill.
W
Power & VAM = (all three forces) × speed, plus a drivetrain loss. VAM is the vertical metres you gain per hour.

Because gravity dominates, weight and gradient drive almost everything on a climb. That is why power to weight matters more than raw watts uphill, and why a lighter, fitter rider climbs faster for the same effort.

Want a printable climbing power chart?
A one-page watts-by-gradient reference chart is coming soon to our shop.
FAQ

Climbing power FAQ

It depends mostly on your total weight, the gradient and your speed. As a rough guide, an 84 kg rider plus bike climbing a 6 percent grade at 8 mph needs around 210 watts. Steeper gradients, more weight or higher speed all push the number up quickly, because on a climb most of your power fights gravity.

The calculator adds three resistances: gravity (your weight times the slope), rolling resistance (tyres on the road) and air drag (which rises with the square of speed). It multiplies the total force by your speed to get power at the wheel, then adds a small drivetrain loss. On steep climbs gravity dominates and aero barely matters.

On a climb you are lifting your own body and bike against gravity, so what matters is watts per kilogram, not raw watts. A lighter rider needs fewer watts to climb at the same speed. That is why W/kg predicts climbing performance far better than watts alone, and why this tool shows both.

VAM stands for velocita ascensionale media, or average ascent speed. It is the vertical metres you climb per hour. A VAM around 1000 metres per hour is strong amateur climbing; elite pros on a hard mountain can exceed 1600. It lets you compare climbs of different length and gradient on one number.

A little. On a steep climb, shaving one kilogram off your total weight is worth roughly one percent less power at the same speed. It helps, but rider weight and fitness dwarf bike weight, so train and fuel before you spend heavily on grams.

Enter the steady speed you expect to hold on the gradient, not your flat-road speed. On a 6 to 8 percent grade many recreational riders hold 6 to 9 mph, while fit riders manage 10 to 12. If you are not sure, try a few speeds and see which power output feels realistic for you.