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Calories Burned Cycling: How the Numbers Are Actually Calculated
Every calorie calculator, fitness watch, and gym bike is doing a version of the same equation, and understanding it tells you exactly how much to trust the number. The standard method uses METs — metabolic equivalents — from the Compendium of Physical Activities, the reference database exercise scientists have maintained since 1993.
The formula
Calories = MET × weight in kg × hours. One MET is roughly your resting burn (about 1 kcal per kg per hour). Cycling MET values scale with speed:
| Speed | Effort | METs | 155 lb rider, 1 hr | 200 lb rider, 1 hr |
|---|---|---|---|---|
| <10 mph | Leisure | 5.8 | ~408 kcal | ~526 kcal |
| 10–11.9 mph | Light | 6.8 | ~478 kcal | ~617 kcal |
| 12–13.9 mph | Moderate | 8.0 | ~563 kcal | ~726 kcal |
| 14–15.9 mph | Vigorous | 10.0 | ~703 kcal | ~907 kcal |
| 16–19 mph | Fast | 12.0 | ~844 kcal | ~1089 kcal |
A 155 lb rider is 70.3 kg, so an hour at 13 mph is 8.0 × 70.3 × 1 ≈ 563 kcal. Note these Compendium figures assume continuous riding at that speed; a casual hour that includes coasting and stops lands meaningfully lower, which is why 250–300 kcal is a more honest expectation for a truly easy hour.
Why your watch disagrees
Three reasons. First, devices with heart-rate data estimate effort directly instead of inferring it from speed, which handles hills and wind better. Second, some report gross calories (including what you would have burned resting) while others report net exercise calories — a difference of 70–100 kcal per hour. Third, a power meter is the only device that measures work directly; its calorie figure (kilojoules ≈ kcal, thanks to ~24% human efficiency) is accurate within a few percent, while speed-based estimates can miss by 20–30% in hilly or windy conditions.
Making the estimate useful anyway
For weight management, consistency beats precision. Use the same method every ride and the errors cancel out of your week-to-week comparison. Two practical anchors: at moderate effort most riders burn roughly 40–50 kcal per mile per 100 lb of body weight is an overestimate people repeat — the honest flat-ground figure is closer to 25–35 kcal per mile for average-sized adults, rising with speed and gradient. And a common planning mistake: eating back every estimated calorie. If weight loss is the goal, eat back no more than half the estimate, since estimates skew high. See our full guide to cycling for weight loss, or get your number now in the calculator.
Keep exploring
Put these numbers to work with the free CalculateBike speed and calorie calculator, browse the cycling gear guide, or read more cycling articles. Prefer two feet to two wheels? Our sister tools CalculateSteps and CalculateRun cover walking and running.