MariposasCalories Burned Calculator
By Zachary, builder of Mariposas · Reviewed against published exercise-science sources (references)
· Last updated June 2026
Nutrition & Calories Pick an activity, enter your weight and how long you did it, and this calculator estimates calories burned using its MET (metabolic equivalent) value: calories = MET × weight in kg × hours. MET values follow the Compendium of Physical Activities.
⚕️ A general-information estimate from population-level formulas, a starting point, not a precise measurement and not medical advice.
How it works
The calculator uses the standard MET-based energy expenditure equation: calories = MET × body weight in kilograms × duration in hours. MET, or metabolic equivalent of task, expresses how much energy an activity demands relative to sitting quietly, which is defined as 1.0 MET. A MET value of 6, for example, means the body is working at six times its resting metabolic rate. The MET values used here follow the Compendium of Physical Activities, a research database originally published by Barbara Ainsworth and colleagues that has been updated across multiple editions and is the standard reference in exercise science for population-level energy expenditure estimates. One important nuance: this formula estimates gross caloric expenditure, meaning it includes the calories your body would have burned just existing during that time, not purely the "extra" calories from moving.
When to use it
This calculator is useful for anyone tracking energy balance, whether that means planning how activity fits into a nutrition target or simply building awareness of how different types of movement compare in caloric cost. It's especially practical when logging workouts in a food diary app that asks for calories burned, or when comparing two activities of equal duration to see which carries a higher metabolic demand. Coaches and curious exercisers alike use MET-based estimates to make informed programming decisions without needing lab equipment.
Worked example
Say a 180-pound person (roughly 81.6 kg) goes for a moderate-pace recreational bike ride for 45 minutes. A moderate cycling effort typically carries a MET around 5.8 per the Compendium. Converting 45 minutes to 0.75 hours and plugging in: 5.8 × 81.6 × 0.75 gives approximately 355 calories. That number tells you the ride consumed a meaningful chunk of energy, roughly equivalent to a substantial snack, but it also illustrates why duration and body weight both pull a lot of weight in the final figure. If that same person rode for 90 minutes instead, the estimate doubles to around 710 calories, which is a useful reminder that time on task is often more controllable than intensity for most recreational exercisers.
Tips for an accurate result
- Use your actual body weight at the time of the activity, not a goal weight. Because weight is a direct multiplier in the formula, even a 10-pound difference shifts the result noticeably.
- Choose the activity description that most closely matches your real effort level. The Compendium lists multiple entries for many activities, such as walking at 2.5 mph versus 3.5 mph, and picking the wrong one can swing the estimate by 30 percent or more.
- For strength training sessions, note that MET values for resistance exercise tend to be lower than people expect, typically in the 3 to 6 range depending on intensity. The calorie burn is real but the number is often smaller than the same time spent on cardio.
- Think of the output as a ballpark, not a precise accounting. MET-based formulas don't account for individual fitness level, heat, terrain, or metabolic efficiency, so real-world values can vary by 10 to 20 percent in either direction from the estimate.
- If you're logging against a food diary, be consistent in your method. Using the same calculator with the same activity codes every week gives you a reliable relative measure over time, even if the absolute number isn't perfect.
Formula & sources: methodology · references.
Now go hit the number Mariposas turns every workout, run and class into progress · collect a cute pet 🐾FAQ
- Why does my fitness tracker show a different number than this calculator?
- Wearable devices layer in additional data, your heart rate, movement patterns captured by accelerometers, sometimes skin temperature, to try to personalize the estimate beyond what a weight-and-MET formula can do. Neither method is perfectly accurate against a metabolic cart in a lab, but they're also measuring slightly different things. Some devices report net calories (subtracting resting metabolism), while MET-based formulas typically report gross calories, which is one common source of discrepancy.
- Does this account for the afterburn effect, or EPOC?
- No. The formula calculates energy used during the activity window itself. Excess post-exercise oxygen consumption, the elevated calorie burn that continues after intense exercise ends, is real but highly variable and depends on workout intensity, fitness level, and other factors. For most moderate-intensity sessions it's a relatively small addition. High-intensity interval training and heavy resistance work tend to produce more EPOC, but quantifying it reliably without lab measurement is difficult.
- How does body weight affect the result so much?
- Moving a heavier body requires more muscular effort and cardiovascular output to perform the same task. A 250-pound person and a 130-pound person doing the same 30-minute jog are doing fundamentally different amounts of mechanical work, even if they cover the same distance. Because weight is a direct linear multiplier in the MET equation, the heavier person will always burn more calories in that session, all else equal.
- Are MET values the same for everyone?
- They represent population averages derived from research studies, so they're a reasonable middle estimate for most adults. People who are highly trained tend to perform a given activity more efficiently and may burn slightly fewer calories than the estimate suggests. Beginners or people carrying more body fat relative to muscle may burn somewhat more. Age, altitude, and even how long you've been doing a specific activity can shift individual numbers away from the MET average.
- Can I use this calculator for everyday activities like housework or walking?
- Yes, the Compendium includes hundreds of activities well beyond structured exercise, from vacuuming and grocery shopping to gardening and childcare. Those entries are genuinely useful for understanding total daily energy expenditure, not just gym time. The same formula applies, and the results can be eye-opening: an hour of vigorous yard work can rival a moderate gym session in caloric cost.