Every calorie-burn figure you’ve seen — on a treadmill display, a smartwatch, a gym poster — comes from the same underlying idea. It’s worth understanding, partly because it lets you sanity-check the numbers, and partly because it explains why they’re so often wrong.
Calories Burned
What a session actually costs, scaled to your bodyweight.
Method: kcal = MET × 3.5 × kg ÷ 200 × minutes, using values from the Compendium of Physical Activities. This is gross burn, so it includes the calories you would have burned sitting still over the same period.
Estimates only — general education, not medical advice. Talk with your doctor before changing how you eat or train. More tools at whatshouldiweigh.com.
What a MET is
A MET is a metabolic equivalent of task — a multiple of what you burn sitting still.
One MET is rest. Walking at 3 mph is 3.5 METs, so it costs three and a half times your resting rate. Running at 6 mph is 9.8 METs. Jumping rope is 12.3.
The calculation:
Calories per minute = MET × 3.5 × your weight in kg ÷ 200
The values come from the Compendium of Physical Activities, a research database that has catalogued the energy cost of hundreds of activities since 1993. It’s the source behind essentially every calorie-burn estimate in consumer fitness.
Why your bodyweight is in the formula
Moving a heavier body costs more energy. A 250-pound person walking a mile burns considerably more than a 150-pound person walking the same mile at the same pace — roughly 65% more.
This has a consequence worth knowing about: as you lose weight, the same workout burns less. Someone who has dropped 40 pounds is burning noticeably fewer calories on their usual run than when they started, at the same pace and distance. It’s one of several reasons progress slows, and it’s not a sign anything has gone wrong.
Gross versus net, and why it matters
This calculator, like almost all of them, reports gross burn — every calorie used during the activity, including the ones you’d have burned anyway just existing.
An hour of moderate cycling might show 500 calories. But sitting on the sofa for that hour would have cost you around 75. The extra cost of choosing to cycle — the net figure — is closer to 425.
For a single session it’s a minor distinction. For someone eating back their exercise calories every day, it compounds into several hundred calories a week that were never really earned.
The tracker problem
Wrist-worn devices and cardio machines routinely overstate burn. Research comparing consumer trackers against laboratory measurement has repeatedly found errors of 20% or more for energy expenditure, and typically worse for activities that aren’t steady-state walking or running.
Heart rate, which is what most wearables infer burn from, is an indirect proxy. It rises with caffeine, heat, stress, dehydration and poor sleep — none of which mean you’re burning more. Weight training is particularly badly estimated, because heart rate spikes between sets while actual energy cost stays modest.
Cardio machines are often worse, especially ones that never asked your weight.
The practical response isn’t to abandon the numbers, it’s to treat them as relative rather than absolute. A tracker that consistently reads 20% high is still useful for comparing this week to last week. It’s just a poor basis for deciding what to eat.
Exercise is a weak lever for weight loss and an excellent one for health
Worth being straight about this, because the calculator above can encourage the opposite conclusion.
A hard 45-minute session might burn 400 calories. That’s a large muffin. Most people can undo an entire workout with one absent-minded snack, and there’s decent evidence that appetite rises to partially compensate for exercise anyway.
Diet is the more powerful lever for changing your weight. It isn’t close.
But that’s a narrow measure of what exercise is for. Regular activity improves cardiovascular health, insulin sensitivity, blood pressure, bone density, sleep, mood and cognitive function — and it’s the single best predictor of whether someone keeps weight off once they’ve lost it. Preserving muscle during a deficit depends on resistance training in a way that no diet adjustment can replace.
Judge exercise by those things. The calorie figure is the least interesting thing it does.
NEAT — the burn nobody counts
Non-exercise activity thermogenesis is everything you do that isn’t deliberate exercise: walking to the car, standing, cooking, fidgeting, gesturing while you talk.
It varies enormously between people — several hundred calories a day between two individuals of similar size — and it’s a bigger contributor to daily burn than most people’s workouts.
It also drops when you’re in a deficit, without you deciding to move less. You sit down sooner, take the lift, fidget less. That quiet reduction is part of why sustained dieting slows down.
Which is why “add 2,000 steps” often outperforms “add another gym session.” It’s easier, it doesn’t spike appetite the way hard training can, and it directly counters the NEAT decline.
Common questions
How many calories does walking burn? At 3 mph, roughly 3.5 METs. For a 180-pound person that’s about 275 calories an hour. Brisk walking at 4 mph raises it to around 390.
Why does my watch say something different? Wearables estimate from heart rate, which is an indirect proxy affected by caffeine, heat, stress and sleep. Both numbers are estimates; the watch’s tends to run high.
Should I eat back my exercise calories? Generally not in full. The figures are inflated, they’re gross rather than net, and if you used a TDEE calculator your activity is already counted in the multiplier.
Which exercise burns the most? Per minute, jumping rope and fast running lead. But the exercise you’ll do three times a week for a year beats the one that burns more and gets abandoned.
Does building muscle raise my daily burn much? Less than commonly claimed. Muscle burns roughly 6 calories per pound per day at rest against fat’s 2 — a real difference, but adding 10 pounds of muscle adds only about 40 calories a day. Muscle is worth building for many reasons; metabolic rate is a minor one.
The calculators on this site are educational estimates, not medical advice. Talk with your doctor before starting a new exercise programme, particularly if you have a heart condition or have been inactive for a long period.