The Quick Answer
Calories burned during exercise are estimated using MET (Metabolic Equivalent of Task) values. The formula is:
Calories burned = MET × body weight in kg × duration in hours
MET is a standardized number that represents how much energy an activity costs relative to sitting at rest. Walking at 3 mph is about 3.3 METs — meaning it burns 3.3 times more energy than sitting still. Running at 7 mph is 9.8 METs.
Example: A 75 kg person jogging at 6 mph (MET 8.3) for 30 minutes: Calories = 8.3 × 75 × 0.5 = 311 kcal
This is the formula behind most calorie calculators, fitness trackers, and exercise apps.
What Is a MET Value?
MET stands for Metabolic Equivalent of Task. It is a unit that expresses the energy cost of a physical activity as a multiple of resting metabolic rate.
- 1 MET = the energy you expend sitting quietly
- 1 MET ≈ 1 kcal per kilogram of body weight per hour
- 1 MET ≈ 3.5 mL of oxygen consumed per kilogram per minute (the physiological definition)
When an activity is rated at 6 METs, it means your body uses about 6 times more energy than at rest. A 70 kg person at rest burns about 70 kcal per hour (1 MET × 70 kg × 1 hour). At 6 METs, that becomes 420 kcal per hour.
The Scientific Basis
MET values are determined through laboratory measurement. Researchers measure oxygen consumption (VO2) during activities using indirect calorimetry — a technique where participants wear a mask that analyzes inhaled and exhaled air. The oxygen consumption during an activity is divided by resting oxygen consumption to produce the MET value.
The most comprehensive collection of MET values is the Compendium of Physical Activities, a research database originally published in 1993 and maintained by Arizona State University. It catalogs MET values for over 800 specific activities, from sleeping (0.95 METs) to competitive running at 10 mph (14.5 METs).
The Formula in Detail
The standard calorie burn formula:
Calories = MET × weight (kg) × time (hours)
This is sometimes written as:
Calories = MET × weight (kg) × (minutes ÷ 60)
Step by Step
- Find the MET value for your activity (see reference table below)
- Convert weight to kilograms if needed (divide pounds by 2.205)
- Convert duration to hours (divide minutes by 60)
- Multiply all three numbers
Worked Examples
Example 1: Brisk walking
- Activity: Walking at 4 mph (MET 4.3)
- Person: 68 kg (150 lbs)
- Duration: 45 minutes (0.75 hours)
- Calories = 4.3 × 68 × 0.75 = 219 kcal
Example 2: Running
- Activity: Running at 7 mph (MET 9.8)
- Person: 82 kg (180 lbs)
- Duration: 25 minutes (0.417 hours)
- Calories = 9.8 × 82 × 0.417 = 335 kcal
Example 3: Swimming
- Activity: Moderate swimming (MET 8.0)
- Person: 60 kg (132 lbs)
- Duration: 40 minutes (0.667 hours)
- Calories = 8.0 × 60 × 0.667 = 320 kcal
Example 4: Light weight lifting
- Activity: Weight lifting, light effort (MET 3.5)
- Person: 75 kg (165 lbs)
- Duration: 60 minutes (1.0 hours)
- Calories = 3.5 × 75 × 1.0 = 263 kcal
Gross Calories vs. Net Calories
There is an important nuance most calorie calculators do not explain: the MET formula calculates gross calories — the total energy your body uses during the activity, including what you would have burned sitting still.
If you want to know the extra calories burned because of the exercise (above what you would have burned doing nothing), you need the net formula:
Net calories = (MET − 1) × weight (kg) × time (hours)
Why This Matters
A 70 kg person sitting at a desk for 30 minutes burns about 46 kcal (MET 1.3 × 70 × 0.5). If that person goes for a 30-minute brisk walk instead (MET 4.3), the gross burn is 151 kcal. But the net additional burn from walking is:
- Net = (4.3 − 1) × 70 × 0.5 = 116 kcal
The difference of 35 kcal is what you would have burned anyway, just existing. For high-intensity activities (MET 8+), the difference between gross and net is small in percentage terms. For low-intensity activities, it matters more.
Most fitness trackers and calorie calculators report gross calories unless otherwise specified.
MET Values for Common Activities
Here is a reference table of MET values for frequently performed activities, with estimated calories burned per 30 minutes for a 70 kg (154 lb) person:
| Activity | MET | Calories (30 min, 70 kg) |
|---|---|---|
| Sleeping | 0.95 | 33 |
| Sitting (desk work) | 1.3 | 46 |
| Standing | 2.0 | 70 |
| Walking slowly (2 mph) | 2.5 | 88 |
| Walking moderately (3 mph) | 3.3 | 116 |
| Walking briskly (4 mph) | 4.3 | 151 |
| Cycling (light, <10 mph) | 4.0 | 140 |
| Cycling (moderate, 12–14 mph) | 6.8 | 238 |
| Cycling (vigorous, 16–19 mph) | 10.0 | 350 |
| Running (5 mph / 12 min mile) | 6.0 | 210 |
| Running (6 mph / 10 min mile) | 8.3 | 291 |
| Running (7 mph / 8.5 min mile) | 9.8 | 343 |
| Running (8 mph / 7.5 min mile) | 11.0 | 385 |
| Running (9 mph) | 12.8 | 448 |
| Swimming (leisure) | 6.0 | 210 |
| Swimming (moderate laps) | 8.0 | 280 |
| Swimming (vigorous laps) | 10.0 | 350 |
| Jump rope | 12.0 | 420 |
| Weight lifting (light) | 3.5 | 123 |
| Weight lifting (vigorous) | 6.0 | 210 |
| Circuit training | 8.0 | 280 |
| Basketball | 8.0 | 280 |
| Soccer | 7.0 | 245 |
| Tennis (singles) | 7.0 | 245 |
| Golf (walking, carrying clubs) | 5.0 | 175 |
| Gardening | 4.0 | 140 |
| Housework | 3.5 | 123 |
| Cooking | 2.5 | 88 |
Source: Adapted from the Compendium of Physical Activities, 2024 revision.
Running vs. Walking vs. Cycling: A Calorie Comparison
One of the most common questions is which cardio activity burns the most calories. Here is a direct comparison for a 70 kg person exercising for 30 minutes:
| Activity & Speed | MET | Calories (30 min) |
|---|---|---|
| Walking, 3 mph (moderate) | 3.3 | 116 |
| Walking, 4 mph (brisk) | 4.3 | 151 |
| Cycling, 12 mph (moderate) | 6.8 | 238 |
| Running, 5 mph (jog) | 6.0 | 210 |
| Running, 6 mph (moderate) | 8.3 | 291 |
| Running, 7 mph (fast) | 9.8 | 343 |
| Cycling, 16 mph (vigorous) | 10.0 | 350 |
Key observations:
- Running burns more per minute than cycling at moderate effort levels
- Vigorous cycling catches up to fast running in terms of calorie burn
- Walking is the lowest burn per minute but is sustainable for much longer and accessible to nearly everyone
- Total calorie burn depends on both intensity and duration — a 60-minute moderate walk can burn more than a 15-minute run
The "best" exercise for calorie burn is the one you will actually do consistently.
How Accurate Are Calorie Burn Estimates?
MET-based calculations are useful approximations, but they have known limitations:
What the Research Says
- A 2018 study in the Journal of Science and Medicine in Sport found that MET-based estimates can deviate by 15–20% from actual measured calorie burn in individual cases
- The standard assumption that 1 MET = 3.5 mL O2/kg/min may overestimate resting metabolic rate, especially in women, older adults, and people with lower fitness levels
- MET values represent averages across a population — individual variation is significant
Factors That Cause Deviation
| Factor | Effect on Accuracy |
|---|---|
| Body composition | Higher muscle mass → higher actual burn than MET predicts |
| Fitness level | Trained athletes may be more efficient at moderate intensities |
| Age | Older adults may have lower resting metabolic rate than the 1 MET assumption |
| Sex | Women tend to have slightly lower resting metabolic rates |
| Terrain and conditions | Uphill, wind, heat, altitude all increase real calorie burn |
| Individual variation | Metabolic rates naturally vary 10–15% between similar people |
More Accurate Alternatives
- Heart rate monitors (accuracy varies by device — generally ±10–15%)
- Chest-strap heart rate monitors (more accurate than wrist-based)
- Lab-measured VO2 (gold standard — measures actual oxygen consumed, but requires lab equipment)
For most people, MET-based estimates are sufficient for general fitness tracking and exercise planning. They are less reliable for precise calorie counting.
How Fitness Trackers Calculate Calories
Smartwatches and fitness bands use a combination of inputs to estimate calorie burn:
- Heart rate data — continuous optical sensor on the wrist
- Accelerometer data — movement intensity and step counts
- User profile — age, sex, weight, height
- Proprietary algorithms — each manufacturer (Apple, Garmin, Fitbit, etc.) uses its own model
Most devices start with MET-like estimates for recognized activities, then adjust based on heart rate. When heart rate data is available, the estimate generally improves.
How accurate are they? Studies show consumer wrist-based devices typically have ±20–30% error for calorie burn. Chest-strap heart rate monitors tend to be more accurate. No consumer device matches lab-grade calorimetry.
Common Mistakes
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Treating estimates as exact numbers. Calorie burn from any calculator or device is an approximation. Use it for general planning, not precise accounting.
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Forgetting to account for resting calories. The gross MET formula includes resting energy. If you are calculating how many "extra" calories you burned through exercise, subtract your resting burn.
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Overcompensating with food. Research consistently shows that people who increase food intake to "replace" exercise calories often eat more than they burned. This is one reason exercise alone is a slow path to weight loss.
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Comparing activities only by MET value. A higher MET does not automatically mean "better." A 30-minute run (MET 9.8) burns more than a 30-minute walk (MET 3.3), but the walk may be more sustainable, lower injury risk, and still beneficial for cardiovascular health.
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Ignoring the time dimension. A low-MET activity performed for a long time can burn more total calories than a high-MET activity performed briefly. Two hours of gardening (MET 4.0) burns more than 15 minutes of running (MET 9.8).
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Using the wrong weight unit. The formula requires kilograms. Using pounds without conversion will overestimate calorie burn by a factor of 2.2.
The Relationship Between Calories, BMR, and TDEE
Understanding how exercise calories fit into the bigger picture:
- BMR (Basal Metabolic Rate): Calories burned at complete rest — breathing, circulation, cell maintenance. Typically 1,200–2,000 kcal/day for adults. This is your baseline.
- NEAT (Non-Exercise Activity Thermogenesis): Calories from daily movements that are not exercise — walking around, fidgeting, standing, doing chores. Often 200–500+ kcal/day.
- TEF (Thermic Effect of Food): Energy used to digest food. Approximately 10% of calorie intake.
- EAT (Exercise Activity Thermogenesis): Calories from deliberate exercise. For most people, this is 200–600 kcal/day on active days.
- TDEE (Total Daily Energy Expenditure): The sum of all four: BMR + NEAT + TEF + EAT.
For most non-athletes, BMR accounts for 60–75% of total daily calorie burn. Exercise (EAT) typically represents only 5–15% of TDEE — which is why diet changes generally have a larger effect on body weight than exercise alone.
This does not diminish the value of exercise. Physical activity improves cardiovascular health, mental health, sleep, bone density, and longevity in ways that dietary changes alone cannot.
Frequently Asked Questions
How many calories does 10,000 steps burn?
For a 70 kg person walking at moderate pace, 10,000 steps (approximately 8 km / 5 miles) takes about 80–100 minutes and burns roughly 350–400 gross kcal. The exact number depends on walking speed, body weight, and terrain. See our steps to miles converter for distance calculations.
Is the "fat-burning zone" real?
The concept is misleading. At lower intensities, a higher percentage of calories come from fat (vs. carbohydrates), but the total calorie burn is lower. Higher-intensity exercise burns more total calories and more total fat calories per unit of time. The "best" intensity for fat loss is the one you can sustain for a meaningful duration.
How many calories should I burn per day through exercise?
There is no single answer. General physical activity guidelines recommend 150–300 minutes of moderate-intensity activity per week (about 1,000–2,000 kcal/week from exercise). Individual goals vary. This is a general wellness guideline — not specific medical advice.
Do you burn more calories exercising in the cold?
Potentially. In cold conditions, your body uses additional energy to maintain core temperature (thermogenesis). However, the effect is modest during exercise because movement itself generates significant heat. You burn slightly more calories in the cold, but not dramatically more.
Why do heavier people burn more calories?
Moving a larger mass requires more energy. Imagine carrying a 20 kg backpack while running — you would burn more calories than running without it. A heavier person's body is essentially moving more weight through space, which requires more force and therefore more energy.
How does muscle mass affect calorie burn?
Muscle tissue is more metabolically active than fat tissue. People with higher muscle mass have a slightly higher resting metabolic rate and tend to burn more calories during exercise. This is one reason strength training is recommended alongside cardio — building muscle increases your baseline energy expenditure.
Can I lose weight by exercise alone?
It is possible but typically slow. Exercise adds 200–600 kcal of burn on an active day, while dietary changes can easily create a larger calorie deficit. Research shows the most effective approach for weight management combines both activity and dietary awareness. Exercise has critical health benefits beyond weight — cardiovascular fitness, mood, sleep, strength, and longevity.
What is EPOC (afterburn)?
EPOC (Excess Post-Exercise Oxygen Consumption) is the elevated calorie burn that continues after exercise ends. Your body consumes extra oxygen to restore muscle glycogen, clear lactate, and repair tissue. After moderate exercise, EPOC adds 5–10% to the session's calorie burn. After very intense exercise (HIIT, heavy lifting), EPOC can add 10–15% or more. The effect tapers off within 1–24 hours depending on intensity.
Try the Calculator
Use our Calories Burned Calculator to estimate your calorie burn for over 30 activities. Enter your weight, select an activity, and see the result instantly — all calculations happen in your browser.
Related tools:
- BMR Calculator — find your Basal Metabolic Rate
- Calorie Needs Calculator — estimate your total daily energy needs (TDEE)
- Pace Calculator — calculate your running or walking pace
- Steps to Miles Converter — convert daily steps to distance
- Heart Rate Zones Calculator — find your training intensity zones