Calories Burned Calculator
Understand how your body expends energy: the science behind MET values, the four calculation modes, and what the numbers really mean for your fitness goals.
Compendium-Based Data
MET values from the 2011 Compendium of Physical Activities (Ainsworth et al.) — the gold-standard reference used by researchers worldwide.
Estimates, Not Measurements
Results are population averages. Always consult a qualified healthcare provider for personalized exercise and nutrition guidance.
What Is Calorie Burn?
Your quick reference for understanding energy expenditure
Every movement you make — from a brisk walk to a sweaty spin class — draws on stored energy. Calorie burn (energy expenditure) is the rate at which your body converts that stored energy into work and heat. The faster and harder you move, and the more you weigh, the more kilocalories you burn per minute.
Quick Answer: Calorie burn ≈ MET × your weight × time — heavier bodies and longer or harder efforts burn more. A 70 kg person walking for 30 minutes burns roughly 129 kcal.
The MET (Metabolic Equivalent of Task) is a ratio: 1 MET = the energy your body uses at complete rest (roughly 3.5 ml O₂ per kg per minute). Walking at a moderate pace is about 3.5 METs — meaning it burns 3.5 times your resting metabolic rate. This simple ratio, multiplied by your body weight and time, gives a reliable estimate of gross caloric expenditure.
The standard ACSM derivation converts oxygen consumption into kilocalories using the fact that burning 1 litre of oxygen releases approximately 5 kcal (the respiratory quotient varies slightly by substrate, but 5 kcal/L is the standard assumption). Combined with the MET definition and a 200-unit conversion factor, this produces the formula below.
kcal = (MET × 3.5 × weight kg ÷ 200) × minutesThe 3.5 in the numerator is the resting oxygen uptake in ml·kg⁻¹·min⁻¹; dividing by 200 converts ml·kg⁻¹·min⁻¹ into kcal·kg⁻¹·min⁻¹ (since 1 L O₂ ≈ 5 kcal and 1 L = 1 000 ml, the factor works out to 200). The result is gross calories — it includes your resting metabolic rate, which is what fitness trackers and most calorie databases report.
Different activities lend themselves to different inputs. The calculator supports four modes:
Duration mode
Enter minutes of activity. The MET formula is applied directly: kcal = (MET × 3.5 × kg ÷ 200) × minutes. Best for gym sessions, yoga, swimming, or anything where you track time.
Distance mode
Enter kilometres (or miles). A per-activity energy coefficient (k kcal·kg⁻¹·km⁻¹) converts distance into calories — walking ≈ 0.53, running ≈ 1.04. Best for outdoor runs, hikes, and bike rides.
Steps mode
Enter your step count. Steps are converted to distance using a 0.762 m average stride length, then the distance formula applies. Best when you have a pedometer or phone step counter.
Reps mode
Enter the number of repetitions for strength exercises. The calculator applies a per-exercise seconds-per-rep estimate and uses MET × seconds-per-rep ÷ 60 to turn each repetition into an equivalent time fraction. Best for push-ups, squats, and other counted movements.
All four modes report gross kilocalories — the same measure used by fitness trackers, food labels, and exercise databases, so you can directly compare burned calories to consumed calories.
Find the MET value
Walking at a moderate pace (about 5 km/h) has a MET of 3.5 according to the 2011 Compendium of Physical Activities. The calculator looks this up automatically when you select the activity.
Plug in body weight and time
Body weight = 70 kg, duration = 30 minutes. Substitute into the formula: (MET × 3.5 × kg ÷ 200) × minutes = (3.5 × 3.5 × 70 ÷ 200) × 30.
Calculate the inner bracket
3.5 × 3.5 = 12.25 → 12.25 × 70 = 857.5 → 857.5 ÷ 200 = 4.29 kcal/min. This is your calorie burn rate at that intensity and body weight.
Multiply by time
4.29 kcal/min × 30 min = ≈ 129 kcal for the full 30-minute walk. A heavier person (e.g. 90 kg) would burn about 165 kcal for the same walk.
Body weight is the single largest driver of calorie burn for a given activity. Because the formula multiplies weight directly, a 90 kg person burns 29 % more than a 70 kg person doing identical exercise.
Intensity (MET value) is the second lever. Running at 9 km/h (MET ≈ 9.8) burns nearly three times as many calories per minute as walking at 5 km/h (MET ≈ 3.5). Small increases in pace or resistance make a bigger difference than most people expect.
Duration scales linearly with calories — double the time, double the burn. This makes long, steady-state activities (walking, cycling, swimming) highly effective for cumulative energy expenditure even at moderate intensity.
Fitness level and EPOC introduce individual variation the formula cannot capture. Trained athletes are more efficient and may burn slightly fewer calories doing the same movement. Conversely, high-intensity intervals produce excess post-exercise oxygen consumption (EPOC) — an elevated metabolic rate for minutes to hours after the session — which this calculator does not include.
Estimates, not measurements
MET values are population averages from lab studies — your actual burn can vary by ±15–20 % depending on fitness level, movement efficiency, terrain, and equipment. The formula assumes a respiratory quotient typical of mixed-fuel metabolism; it is less accurate during very high intensity (near pure carbohydrate) or prolonged fasting (near pure fat) exercise. Results are gross calories (including resting metabolism), not net calories above rest — this is what fitness trackers and food databases report, but it means you should not eat back every calorie the calculator shows without accounting for what you would have burned at rest anyway. This tool is for general fitness awareness, not medical or clinical nutrition planning — consult a healthcare provider or registered dietitian for personalised advice.