How to Estimate Calories Burned During Exercise (Without a Fitness Tracker)
The MET formula estimates calories burned from body weight, activity, and duration. Here is the math, the limits, and a free calculator for 24 common activities.
The <strong>MET formula</strong> is the standard way to estimate calories burned: <code>calories = MET × weight(kg) × hours</code>. Walking is 3.5 MET, running is 9.8 MET, cycling is 7.5 MET, swimming is 8.0 MET. The <a href="/calorie-burn-calculator">Uttir Calorie Burn Calculator</a> covers 24 activities and lets you enter a custom MET for any activity not on the list.
Wrist-worn fitness trackers are convenient, but the number they report for “calories burned” is an estimate, not a measurement. The same is true of any gym equipment readout. For most people, an estimate based on the MET formula is within 10-20% of a lab measurement — close enough for planning, too rough to call a measurement.
This post walks through what the MET formula is, what it does well, where it falls apart, and how to use a free calculator that runs in your browser.
The MET formula
MET stands for Metabolic Equivalent of Task. 1 MET is the energy cost of sitting quietly, about 1 kcal per kg of body weight per hour. Every activity has a MET value:
- Sleeping: 0.95 MET
- Sitting quietly: 1.3 MET
- Walking, 3 mph: 3.5 MET
- Walking, 4 mph: 5.0 MET
- Cycling, 12-14 mph: 8.0 MET
- Running, 5 mph: 8.3 MET
- Running, 6 mph: 9.8 MET
- Swimming, moderate: 7.0 MET
- Swimming, vigorous: 9.8 MET
- Weight training, vigorous: 6.0 MET
- HIIT: 8.0 MET
- Yoga: 2.5 MET
The formula:
Calories burned = MET × body weight (kg) × duration (hours)Worked example: a 75 kg person running at 6 mph (9.8 MET) for 45 minutes:
9.8 × 75 × 0.75 = 551 caloriesThat is the same answer most fitness watches would give for the same input, because most of them use the MET formula under the hood.
What the formula does well
- Comparing two activities. Running for 30 min vs. walking for 60 min — the formula gives a clean relative answer.
- Planning a weekly calorie target. “I want to burn 2,000 kcal/week through exercise” — the formula tells you which activity + duration combinations hit that.
- Comparing across body weights. Heavier people burn more; the formula captures that correctly.
- Activity-agnostic. It works for any activity with a published MET, including occupational tasks (carpentry, farming, cleaning).
Where the formula falls apart
- It does not account for fitness level. A trained cyclist at 200 W might be working at 12 MET, while an untrained cyclist at the same power output is working at 7 MET. The formula averages them.
- It does not account for terrain, wind, or heat. Running on sand vs. running on a treadmill changes the cost by 20-30%.
- It uses body weight as a proxy for muscle mass. A 75 kg bodybuilder burns more than a 75 kg sedentary person at the same activity. The formula treats them as equal.
- It does not capture “afterburn” (EPOC). High-intensity intervals keep the metabolism elevated for hours after the workout. The formula credits the workout only, not the recovery burn.
- It is a population average. For any one person, the real number can be 30% higher or lower. The formula is an estimate, not a measurement.
Common activities and their MET values
| Activity | MET | 75 kg person, 30 min |
|---|---|---|
| Walking, 3 mph | 3.5 | 131 kcal |
| Walking, 4 mph | 5.0 | 188 kcal |
| Running, 5 mph | 8.3 | 311 kcal |
| Running, 6 mph | 9.8 | 368 kcal |
| Cycling, 12-14 mph | 8.0 | 300 kcal |
| Swimming, moderate | 7.0 | 263 kcal |
| Rowing, moderate | 7.0 | 263 kcal |
| Elliptical, moderate | 5.0 | 188 kcal |
| Weight training, vigorous | 6.0 | 225 kcal |
| HIIT | 8.0 | 300 kcal |
| Yoga | 2.5 | 94 kcal |
| Pilates | 3.0 | 113 kcal |
| Hiking | 6.0 | 225 kcal |
| Basketball | 6.5 | 244 kcal |
| Soccer | 7.0 | 263 kcal |
| Tennis, singles | 7.3 | 274 kcal |
How to run the math for yourself
The Uttir Calorie Burn Calculator covers 24 common activities with the right MET for each, plus a custom-MET option for anything not on the list. Enter your weight, pick the activity, set the duration, and the answer comes out in kcal. It runs in your browser with no upload.
For related numbers, the Uttir BMI Calculator covers body composition (the right input for the MET formula), and the Uttir Pace Calculator is the right tool for runners and cyclists who want to plan by time and distance instead of duration.
Bottom line
Calories burned during exercise are an estimate no matter how you slice it. The MET formula is the standard, the formula your fitness watch uses under the hood, and a defensible approximation for planning. Use the Uttir Calorie Burn Calculator for the math, treat the result as ±20%, and use it to compare activities rather than to count toward a daily budget.