Understanding mets and calories burned helps explain why activity intensity changes a calorie estimate. A MET represents the energy demand of an activity relative to rest: the higher the MET value, the higher the estimated calorie use for the same body weight and duration. These figures are practical estimates, not direct measurements of an individual’s energy expenditure.
A calories burned calculator combines an activity’s MET value with body weight and time. This makes it useful for comparing activities or planning sessions, provided the result is interpreted with its limitations in mind.
What does a MET mean?
MET stands for metabolic equivalent of task. One MET represents the conventional estimate of energy use while resting. An activity assigned 5 METs is estimated to require about five times the energy used at rest.
MET values provide a standard way to describe activity intensity. The 2024 Adult Compendium of Physical Activities, for example, organises activities and assigns standardized MET values for research and estimation.
A MET value describes the typical energy demand of an activity, not how difficult it feels to every person. The same activity may feel comfortable to one person and demanding to another because fitness, skill, health, pace and environmental conditions differ.
How mets and calories burned are connected
METs supply the intensity part of a calorie calculation. Body weight and duration supply the other main inputs. When weight and time remain unchanged, a higher MET value produces a proportionally higher calorie estimate.
For example, an 8-MET activity produces twice the estimated energy expenditure of a 4-MET activity when performed by the same person for the same number of minutes. Similarly, doubling the duration doubles the mathematical estimate if MET and body weight stay unchanged.
This relationship does not mean the estimate captures every physical difference between people. MET tables use standardized values, while an individual’s actual energy expenditure can vary even when the activity description appears to match.
How the calories burned calculator uses METs
The calculator applies the following commonly used equation:
Estimated kcal = MET × 3.5 × body weight (kg) ÷ 200 × minutes
Each part has a specific role:
- MET: represents the estimated intensity of the selected activity.
- Body weight: adjusts the estimate for the person’s mass and is entered or converted to kilograms for the formula.
- Minutes: represents how long the activity was performed.
- 3.5 and 200: are constants used in this standard MET-based calculation.
The result is an estimate in kilocalories, commonly shortened to kcal or described as calories on food labels and activity tools. Because MET is defined relative to rest, the formula generally estimates total energy use during the activity period. It may not match a device’s “active calories” figure if that device subtracts estimated resting energy.
A MET calculator may allow direct entry of a MET value, while an activity-based tool may associate selected activities with standard MET values. Either approach depends on how closely the chosen value represents the activity actually performed.
Practical example: 80 kg for 30 minutes
Consider a person weighing 80 kg who performs an activity rated at 5 METs for 30 minutes. The calculation is:
- Multiply 5 METs by 3.5: 17.5.
- Multiply 17.5 by 80 kg: 1,400.
- Divide 1,400 by 200: 7 kcal per minute.
- Multiply 7 by 30 minutes: approximately 210 kcal.
The estimated result is therefore about 210 kcal. It should be read as a planning figure rather than a measured total.
The table below shows how changing only the MET value affects the estimate for the same 80 kg body weight and 30-minute duration.
| Illustrative intensity | MET value | Estimated calories |
|---|---|---|
| Lower-intensity example | 3 METs | 126 kcal |
| Middle example | 5 METs | 210 kcal |
| Higher-intensity example | 8 METs | 336 kcal |
These examples are mathematical comparisons, not promises about what a particular person will expend. If pace, terrain or effort changes during the session, one fixed MET value may not represent the entire 30 minutes.
What the calculator can and cannot tell you
What it can estimate
A calories burned calculator can provide a consistent estimate based on the information entered. It is particularly useful for comparing how changes in activity intensity, duration or body weight affect the result under the same formula.
- Approximate calories used during a selected activity period
- The effect of choosing a different MET value
- The estimated difference between shorter and longer sessions
- A standardized basis for comparing activity options
What it cannot measure
The calculator does not directly measure oxygen consumption, heat production or an individual’s metabolism. It also cannot confirm that a standard MET value perfectly matches a person’s pace, technique or conditions.
- Your exact energy expenditure
- How difficult the activity feels to you
- Changes in intensity within a mixed or interval session
- The accuracy of a wearable device or exercise machine
- How many calories should be eaten or reduced
Exercise calories are only one part of total daily energy use. A single activity estimate should not be treated as a complete measure of daily energy needs or as a precise allowance for food intake.
Why actual energy expenditure can differ
The formula assumes that the selected MET value reasonably represents the activity. In practice, a broad description such as walking, cycling or household work can include many different speeds and effort levels.
Several factors can move actual expenditure away from the estimate:
- Pace and effort: A faster or more forceful version of an activity may have a different MET value.
- Terrain: Hills, uneven ground and surface conditions can change the effort required.
- Fitness and movement efficiency: People may use energy differently while completing the same external task.
- Technique and equipment: Form, resistance settings and equipment design can affect workload.
- Environment: Temperature, wind and other conditions may alter physical demand.
- Input accuracy: An incorrect weight, duration or activity selection changes the calculated result.
Wearables and cardio machines may show different numbers because they can use proprietary equations, sensor data and different definitions of activity calories. A difference does not automatically establish which figure is correct; both may be estimates based on different assumptions.
For consistent comparisons, use the same method and select the activity description that most closely matches the session. Interpreted this way, mets and calories burned offer a useful framework for understanding intensity without implying measurement-level precision.
Frequently asked questions
Does a higher MET always mean I personally worked harder?
A higher MET indicates a greater standardized energy demand for the listed activity. Personal effort can feel different because fitness, experience and conditions vary. MET and perceived difficulty are related concepts, but they are not identical.
Why does body weight affect the calorie estimate?
Body weight is a direct input in the MET equation. For the same MET and duration, a higher entered weight produces a higher estimate. This is a feature of the formula and does not represent a judgement about fitness or health.
Will doubling my exercise time double the estimated calories?
Yes, mathematically, if body weight and MET remain constant. A 60-minute estimate will be twice a 30-minute estimate under those assumptions. In real sessions, intensity may change as pace, terrain or fatigue changes.
Why is the calculator result different from my watch?
A watch may use heart rate, motion sensors, personal settings and its own calculation method. It may also report active calories rather than total energy used during the activity period. These differences can produce results that do not match the standard MET formula.
Can I use one MET value for interval training?
One value can provide a rough overall estimate, but it may not reflect alternating periods of high and low intensity. A more detailed estimate would calculate separate segments using the relevant MET value and duration for each, then add the results.