Calories Burned Calculator

Online calorie burn calculators all work on the same basic principle - they multiply your weight by the intensity of the activity and then by the duration. The difference is how the intensity is determined and how honest you are about information that you don't know yourself. This tool offers four methods for inputting data: based on activity, distance traveled, heart rate or back-calculating from a target calorie burn. It also shows both the values reported by your device as well as an estimate of what the actual calories burned would be.

A difference of five per cent separates the formula and these two versions.

Almost everything that's covered here is based on a single equation.

The MET (Metabolic Equivalent of Task) is a multiple of the resting metabolic rate. One MET is defined as the amount of energy expended while sitting quietly and is usually taken to be an oxygen consumption of 3.5 ml per minute per kilogram body weight. An activity with a value of 8 METs therefore requires eight times more oxygen. As burning one litre of oxygen releases about 5 kcal, we can convert the oxygen in millilitres into kilocalories by dividing by 1000 and then multiplying by 5 - so 200 is calculated.

When fully implemented, one MET is equivalent to an expenditure of 1.05 kcal per hour per kilogram of body weight, not 1.00. This difference is important because many calculators use this truncated formula.

In the abbreviated formula a value of 1.00 is assumed for each MET, leading to results that are about five percent lower. Both calculation methods are scientifically sound and widely used, but few indicate which method they have used.

If you compare two calculation tools and find that there are small, inexplicable differences in the results, it is usually for one of these reasons:

Where do the MET values come from and what does it mean?

The MET values in the activity list are based on data from the publicly available "Physical Activity Factsheet". Both Harvard Health and the American Cancer Society as well as most major calculators refer to this same table. These are average values obtained by measuring groups of people, and do not represent an individual prediction for you. There are three factors that can cause your actual values to deviate from this table, but none of the calculators can account for these.

The last point is a bit complicated but the source is right to highlight it. The 3.5 ml per minute and kg body weight reference value is based on a standardised subject: a healthy man aged 40 with a weight of 70kg. If your basal metabolic rate is significantly lower than this - which is often the case for smaller people or older people - then all the MET-based values you see will appear to be by the same percentage higher.

Why does distance mode use a different calculation type?

If you are walking, running or cycling a particular distance in a particular time then there is no need to select training intensity. The speed will be the distance divided by the time and this speed directly determines the intensity.

The fuel consumption on level ground corresponding to this speed is determined from publicly available reference values. Interpolation methods are used to determine the values between the reference points; nearest neighbor interpolation is not used. When driving at a speed of 6.3 mph, the calculator calculates a value of 6.3 mph and does not round it down to the range of 6.0.

It may seem wrong but it is correct that walking at 5 mph and running at 5 mph have the same MET value. At this speed walking becomes a type of fast walk and the expenditure is similar to light jogging. Most people start running before then because it is no longer efficient to keep walking.

For bikes the calculation is different because published bike values are not for individual points but for speed ranges: under 10 mph, from 10 to 12, from 12 to 14. The tool treats these ranges in steps and does no continuous smoothing. Interpolations would create accuracy that was not present in the original data.

The most energy-efficient walking speed is about 3 miles per hour.

When you convert these reference values from the amount consumed per minute to the amount consumed per mile, it leads to conclusions that few people address. The calorie consumption of walking a mile is U-shaped.

Around 3 mph is the most efficient gait. If you walk slower than this speed, then for a longer period of time you will be expending energy that is only needed to maintain an upright position. If you exceed this speed significantly, then the biomechanics of walking begin to place stress on your body. Most people switch from walking to running at around 4.5 mph.

Running is the opposite and changes are much less. At about 122 kcal per mile at a pace of 5 mph, then it's 107 kcal at a pace of 10 mph for the same 70 kg runner. So if you're looking at calories per mile rather than calories per hour, brisk walking is slightly more efficient than slow walking and fast running is slightly more efficient than slow running.

If you want to burn more calories, either increase the distance or increase the incline. If you walk faster, then there is a greater effect per hour but very little effect per mile.

How much does incline increase calorie burn?

There are publicly available metabolic equations for calculating the incline both walking and running. This tool adds the incline factor to the calories burned on level ground.

S is the speed in meters per minute, g is the grade as a decimal fraction and c is 1.8 for walking and 0.9 for running. Dividing by 3.5 converts the extra value into METs. Only the grade factor is used here. The flat part of the same equations was simulated on a treadmill and at walking speeds it came out about fifteen percent lower than real measurements, so the data from the table for calories burned on level ground are used here.

A person (weighing 70 kg) walking 5 km in 60 minutes at a speed of 3.11 mph on level ground is doing 3.67 METs and the pace is 83.3 meters per minute. If this pace is put onto a constant incline of 5 percent, then the incline factor is 1.8 x 83.3 x 0.05 ÷ 3.5 which equals an additional 2.14 METs. Even at a slight incline that you barely notice, this means an increase of 58 percent.

There are two things that this tool does not do intentionally. It doesn't model a situation where a downhill is easier than flat ground. In fact it often will be since on gentle descents the energy expenditure can be less going down hill than on level ground and it hits a minimum of about minus ten percent after which braking becomes more important. So calculating a downhill as flat ground will give a slightly higher number. This point is communicated openly and noted in the product description. The other thing is to completely remove the field for entering the grade for bicycles since there are no generally accepted equations that combine speed and grade for bikes. On a bike the grade doesn't directly change the load at a constant speed but it does affect the speed and this is already included in the values entered.

The heart rate mode and the possibly misleading coefficient:

If you have average values for a single training session from your watch or chest strap, the heart rate mode uses the regression equation of Keytel (2005). These two publicly available equations are basically the basis for almost all online tools to calculate calorie consumption based on heart rate, even if some do not cite sources.

In this formula, HR is the heart rate per minute, W is weight in kilograms and A is age in years. The result is divided by 4.184 to obtain calorie consumption.

The equation is an approximation for constant submaximal intensity exercise and therefore deviates considerably at heart rates below about 90 beats per minute. This is because the differences in resting heart rate between individuals are much larger than the differences in resting metabolic rate. The female equation contains a negative coefficient for weight, which is not physiologically correct; at the same heart rate, a heavier woman should expend more calories. This is an artifact of the regression and is retained here since changing it would make this no longer be the Keytel equation that others have been using surreptitiously.

Why all of the total, net calories and weight explanations are presented here as net values.

MET is a measure of your resting metabolism, so the total calories calculated using METs will always include the calories you would burn if you were to lay down and do nothing for a few minutes.

For a person (weighing 70 kg), the value to be subtracted is about 1.2 kcal per minute, or 74 kcal per hour. With high-intensity running this is only a rounding error. However, for an hour of gardening it makes up a quarter of the total consumption.

The headers on this page show the total calories. This is what a smartwatch will display and can be used for comparison purposes. All values that convert calories to body fat are based on net calories and this is also indicated on the map.

If you're wearing something:

A backpack, weight vest, baby in arms or fully loaded stroller will increase the mass you are moving and thus energy expenditure increases almost proportionally to mass. Adding ten kg will increase the workload for a 70kg person by 14 percent, and this is also taken into account in the calculator.

However, no additional load is added to the resting metabolism. Just because you carry a backpack does not mean your metabolism goes up. So in net calories only the extra workloads are added as calories burned. That's what carrying luggage is all about.

Reasons for different values on the clock

There are usually four reasons for this and they can interact with each other.

The last reason is actually the biggest single factor that leads to overestimation. A tennis match with breaks is not the same as an hour of continuous tennis. The MET values are measured for continuous activity. If the entered time is actual movement time and not total elapsed time, then the result will be increased by the same percentage the longer you stand still.

Calories to weight conversion guide

One kilogram of body fat contains about 7,700 kcal, one pound of body fat contains about 3,500 kcal. If the actual calories burned are divided by either of these values, then you get the amount of fat that is shown on the device.

These numbers may seem small but they are actually quite low. A brisk three-times-a-week walk burns about 546 net kcal, which equates to a fat loss of around 71 grams per week. It takes more than three months to lose one kilogram. The reason why walking can help you lose weight is not because the individual walks have much impact but that this habit can be sustained over the long term. Also, these numbers are based on the assumption that the calories burned will not be replaced by eating, but appetite encourages this very effectively.

A complete example from start to finish.

A person (82kg) walks 5km in 55 minutes on hilly terrain with an average gradient of 4 percent and carrying a backpack weighing 6kg.

Please note that the calories burned will vary depending on your activity level. Carrying a backpack while hiking uphill is included in the total calorie burn because it requires physical exertion. However, it is not factored into the basal metabolic rate calculation because it does not involve any metabolic activity. Also keep in mind how much of an impact the incline has on your calorie burn. If you were to hike the same distance at the same pace on a flat surface, your total calorie burn would be 349 calories. So a four percent incline will add another 79 calories burned, which is roughly equivalent to one small banana.