The Exercise Side of the Energy Equation

Your fitness tracker says 400 calories. Your friend’s app says 250 for the same run. Somebody is wrong — and the honest answer is that both are estimates. Exercise calorie burn depends on three things: how intense the activity is, how long you do it, and how much body weight you are moving. Change any one of them and the number changes with it.

This free calories burned calculator handles the exercise side of the energy equation. Pick from 20 activities, enter your duration and body weight (pounds or kilograms), and it estimates the calories you burned using MET values from the Compendium of Physical Activities — the same reference exercise scientists use. You also get your burn rate per minute and per hour, plus a walking-equivalent so the number means something at a glance. Tracking the intake side instead? That is our TDEE calculator and BMR calculator.

How to Use This Calculator

1. Choose your activity. Select the closest match from the 20-activity dropdown — the MET value in brackets sets the intensity.
2. Enter your body weight. Toggle between pounds and kilograms. A heavier body burns more doing the exact same workout.
3. Enter the duration. Hours and minutes of actual moving time — rest breaks between sets do not count.
4. Click Calculate Burn. Your total calories burned appears at the top.
5. Read the extra stats. Calories per hour, calories per minute, the MET intensity, and the brisk-walk equivalent (how many minutes of brisk walking would burn the same amount).

What Is a MET?

MET stands for Metabolic Equivalent of Task. It is a ratio that compares an activity’s energy cost to sitting still. By definition, 1 MET = sitting quietly. An activity rated at 4 METs burns roughly four times the calories of resting; at 10 METs, ten times.

The MET values in this calculator come from the Compendium of Physical Activities, a research database that standardizes the energy cost of hundreds of activities. That is why a run can be quoted at 9.8 METs rather than a vague “high intensity” — it is a measured, published number, not a guess.

One honest caveat: MET values are population averages. Your actual burn shifts with fitness level, body composition, terrain, temperature, and how efficiently you move. Two people at the same weight can differ by 10–20%. Treat the result as a solid estimate (±20–30%), not a lab measurement.

The Formula (With a Worked Example)

Worked example. A 70 kg person runs at 6 mph (9.8 MET) for 30 minutes:

1. Hours: 30 ÷ 60 = 0.5 hr
2. Calories: 9.8 × 70 × 0.5 = 343 calories

In pounds: a 154 lb person brisk-walking (4.3 MET) for 60 minutes: 154 ÷ 2.20462 = 69.85 kg; 4.3 × 69.85 × 1 = 300 calories. Notice the weight effect — a 200 lb walker doing the identical hour burns about 390.

MET Reference Table

Estimated calories for a 155 lb (70.3 kg) person doing 30 minutes of each activity:

Tips for Reading Your Burn Number

• It is an estimate, not a receipt. Fitness trackers, gym machines, and MET calculators all approximate. Use the number for planning and comparisons — not to “earn” exact food portions.
• Don’t eat back the full burn. Exercise estimates run high, and the body partly compensates by moving less the rest of the day. Most coaches treat workout burn as a small buffer, not a license to eat it all back.
• Weight matters — a lot. Calories scale directly with body weight in the formula, so as you lose weight, the same workout burns fewer calories. That is normal, not a broken metabolism.
• Intensity buys time, not magic. Covering the same distance burns similar calories whether you walk or run — running just finishes sooner and adds a bigger afterburn (EPOC).
• Strength training punches above its number. Its MET looks modest, but it preserves muscle during fat loss, and muscle keeps your resting burn higher.
• Pair burn with intake. A workout number alone does not manage weight — combine it with your daily calorie target (TDEE) and track the weekly weight trend, which is the measurement that actually counts.

Related Tools

The Afterburn Effect (EPOC)

Hard exercise keeps costing calories after you stop. For a while after a vigorous session your body uses extra oxygen to clear metabolic by-products, restore energy stores, and cool down — a phenomenon trainers call the afterburn and scientists call EPOC (excess post-exercise oxygen consumption). Metabolism can stay elevated for 30 minutes to several hours depending on intensity.

Keep the effect in proportion, though: for most workouts the afterburn adds a modest bonus on top of the session itself, not a second workout’s worth of calories. A 70 kg person doing 30 minutes of high-intensity intervals (MET 8) burns 8 × 70 × 0.5 = 280 calories during the session by the formula above — the afterburn sweetens that number slightly, but the session is where the real work happens.