Cycling Calories per Kilometre Calculator

The energy cost of cycling

Cycling is one of the most efficient forms of human movement. A trained cyclist on a road bike at 25 km/h on flat ground burns about 30 to 40 kcal per km, much less than running (about 70 kcal/km) and only modestly more than walking on a per-distance basis. The reason is mechanical: a smooth-spinning bicycle reuses ~95% of pedaling energy as forward motion, with the rest lost to drivetrain friction and tire deformation.

What drives the calorie number

Three factors dominate:

1. Body weight (linear effect): heavier riders burn more per km, but only modestly more on flat terrain. Big effect on climbs.
2. Speed: air resistance rises with the cube of speed, so the cost per hour climbs steeply. Per kilometre the rise is gentler, because you cover the ground faster too. Going from 15 to 30 km/h roughly doubles the calories per hour and adds about half again per kilometre.
3. Terrain: hilly riding costs about 25% more per km than flat here, mountainous about 55%. Climbing is where body weight starts to bite.

The formula

This uses the MET method, which is the standard way to estimate the energy cost of an activity:

kcal per hour = MET × body weight in kg

kcal per km = kcal per hour ÷ speed

A MET is a multiple of your resting metabolic rate. Cycling runs about 6 METs at a gentle 18 km/h and about 12 at a brisk 30, and this page adds a terrain multiplier of 1.0 flat, 1.25 hilly, 1.55 mountainous on top.

A reality check

These come straight out of the calculator, so you can reproduce any row:

How much to trust these

Less than the decimal places suggest. MET tables are built from averages across study populations, and they run high compared with what a power meter says: work out the actual mechanical power for a 75 kg rider holding 20 km/h on the flat and you get around 70 watts, which even at a generous 20% efficiency is nearer 300 kcal an hour than 600.

The gap is real and it is not a mistake in either method. METs measure your whole metabolism including the part that would have been running anyway; a power meter measures only what reached the pedals. For fuelling on the bike, the MET figure is the more useful of the two, since your stomach does not care which category the calories came from. For weight-loss arithmetic, treat it as an upper bound and be honest that appetite closes most of the gap anyway.

Why it matters for nutrition

If you are bonking on long rides, you almost certainly under-eat on the bike. Most recreational cyclists need 30 to 60 g of carbs per hour beyond ~90 minutes of riding. Trained endurance riders push 80 to 120 g/hour using glucose-fructose blends. Use the calorie estimate as a rough fueling target, not a weight-loss accounting tool — your body burns fat preferentially at low intensity and carbs preferentially at high intensity, and a calorie out is not a calorie out from the same fuel tank.