Calorie Burn Calculator
How much is that workout actually worth? Pick an activity, add your weight and duration — the math is the same MET method researchers use, and the answer comes with an honest reality check about what exercise can and can't do for the scale.
Your workout
This calculator gives population-level estimates from published MET values — individual burn varies with fitness, body composition, and terrain. It is a planning aid, not medical advice.
Where the Burn Number Comes From
The calculator uses the Compendium of Physical Activities — the research standard catalog that assigns every activity an intensity score called a MET (metabolic equivalent of task). One MET is the cost of sitting still; a 9.8-MET run burns roughly ten times that. The conversion is simple and transparent: kcal per minute = METs × 3.5 × body weight in kg ÷ 200. Heavier bodies pay more for the same movement — which is why the number shrinks as you lose weight, and why the calculator needs your honest current weight.
Intensity nudges the MET value up or down: the calculator adjusts your selected activity by roughly ±15% for light or vigorous effort, anchored to the talk test you can do mid-workout — if you can sing, you are light; if you can talk but not sing, moderate; if you can only manage a few words, vigorous. The Compendium's own listing documents each code in full.
Typical MET values behind the picks
| Activity (moderate pace) | METs | 30 min at 165 lb |
|---|---|---|
| Walking — casual (2 mph) | 2.8 | ~118 kcal |
| Walking — brisk (3.5 mph) | 4.3 | ~181 kcal |
| Hiking — cross-country | 6.0 | ~252 kcal |
| Running — easy (5 mph) | 8.3 | ~349 kcal |
| Running — hard (7.5 mph) | 11.0 | ~462 kcal |
| Cycling — easy (10-12 mph) | 6.8 | ~286 kcal |
| Swimming — laps, moderate | 5.8 | ~244 kcal |
| Weight lifting — vigorous | 6.0 | ~252 kcal |
| HIIT / circuit training | 8.0 | ~336 kcal |
| Elliptical — moderate | 5.0 | ~210 kcal |
| Rowing machine — moderate | 7.0 | ~294 kcal |
| Jumping rope | 12.3 | ~517 kcal |
| Yoga (hatha) | 2.5 | ~105 kcal |
| House cleaning — vigorous | 3.5 | ~147 kcal |
MET values from the Compendium of Physical Activities (Ainsworth et al.); 30-minute figures computed for an 80 kg person at the listed intensity.
The reality check: exercise and the scale
Here is the part most calorie-burn pages leave out. A 30-minute brisk walk burns about 180 calories — roughly one granola bar. A hard 45-minute gym session earns about 350-450 — roughly one takeout entrée. This is why the kitchen sets the deficit and exercise keeps the engine: sessions burn real calories, but food is where hundreds hide in seconds, and appetite has a way of claiming back a "earned" snack. What exercise genuinely does for weight loss:
- Protects lean mass. Resistance training in a deficit tells the body to keep muscle — the difference between losing weight and losing the right weight (check yours with the body fat calculator).
- Adds honest burn. 5 sessions a week is a real few hundred to a couple thousand extra calories — helpful margin, not a license.
- Regulates appetite and sleep better than any supplement, and both of those drive what happens at the fridge.
Making the burn part of a prep week
The cleanest routine pairs movement with containers: a brisk 30-minute walk at lunch Monday through Friday (≈900 kcal a week at 165 lb), two lifting sessions (≈500), and Sunday's prep session while dinner roasts. That is the CDC's 150-minute weekly target cleared without a gym membership — and the food side is already handled, which is the half that decides the scale. A simple jump rope or a pair of adjustable dumbbells covers the two highest-MET options on this list for the price of one month of a commercial gym.
Frequently asked questions
Why does my watch or gym machine show a different number?
Machines and wearables add inputs this calculator does not use — heart rate, age, sometimes fitness level — but they also tend to flatter. Treadmill consoles routinely overstate burn by 15-25% because they count baseline metabolism you would burn sitting still anyway. The MET formula gives the conservative, population-level number; treat fancier devices as trend meters, not truth meters.
Can exercise offset a bad diet?
Not really — one bakery muffin is roughly a 45-minute brisk walk, and a large fast-food meal can erase a week of sessions. The research summary "you cannot outrun a bad diet" holds: adding exercise without changing food intake produces far less loss than expected. Exercise is for muscle, heart, and appetite regulation; the kitchen decides the deficit.
Does working out fasted burn more fat?
Fasted sessions shift the fuel mix during the workout — more fat, less carbohydrate — but multi-week studies find no meaningful difference in total fat lost versus fed training. Over months, the weekly calorie balance and protein intake decide body composition, not the fuel source of a 40-minute session. Train whenever you will actually train consistently.
How much exercise should I do per week?
The standard target is 150 minutes of moderate activity or 75 minutes of vigorous activity per week, plus two resistance sessions — about 20-30 minutes of brisk walking on most days. That reliably improves health markers and adds a meaningful few hundred calories of weekly burn, but it works alongside a planned deficit, not instead of one.
Where these numbers come from
- Compendium of Physical Activities — MET intensity codes for every activity in the picker (Ainsworth et al.).
- CDC — adult physical activity guidelines: 150 min moderate / 75 min vigorous weekly plus 2 resistance sessions.
- Exercise and diet research — context on why energy intake dominates exercise-only weight-loss outcomes.