Calories Burned Swimming Calculator

Calories burned swimming is an estimate of the energy your body uses during a swim. This calculator works from your weight, how long you swim, which stroke you swim and how hard you work. It is made for adults aged 19 and over.

What Swimming Calories Measure

The result is the total energy you use while swimming, including the energy your body would use at rest in that time. It is not a measure of fat loss, and it does not count calories burned after you leave the pool. Strokes differ a lot. Butterfly costs far more than easy backstroke.

The Formula

The calculator uses the MET method from the 2024 Adult Compendium of Physical Activities¹. A MET is the ratio of the work metabolic rate to the resting metabolic rate, and one MET is defined as 1 kcal per kg per hour².

Calories burned = MET x body weight (kg) x time (hours)

The MET values are copied from the compendium's water activities table³.

How This Calculator Computes Your Result

Enter your weight (kg or lb), your time in minutes, your stroke and your effort. Pounds are converted to kilograms, minutes are converted to hours, and the final answer is rounded to the nearest whole calorie. You also get a table with calories for every stroke and effort at 30 and 60 minutes, using your weight. Time means total time in the water, so include rests.

Butterfly and leisure swimming have only one value in the compendium, so the effort choice does not change those results.

You can also enter your pool length and the number of lengths you swam. This does not change your calories. It shows your pace in yards per minute, so you can compare it to the compendium's freestyle speeds³.

What Your Result Means

Each stroke and effort has its own MET value³. Here is what 30 and 60 minutes burns for a 70 kg (154 lb) adult:

Your own numbers scale with weight. A heavier swimmer burns more in the same time, and a lighter swimmer burns less.

Why Swimming Estimates Are Less Precise

Swimming is harder to estimate than walking or cycling. Water pushes back far more than air. At the same speed, the energy cost is higher in water than on land because of drag and because we are less efficient at pushing against water⁴. Only a small share of the energy a swimmer burns becomes forward motion⁴.

Technique matters a lot. At the same speed, a recreational swimmer can use as much as twice the energy of a skilled swimmer⁴. At the same speed, front crawl costs the least, then backstroke, then butterfly, and breaststroke costs the most⁴. The compendium's MET values are averages, so they cannot capture your own technique.

Body make-up matters too. Water holds you up, so you spend almost no energy staying afloat⁴. Body size, body fat and how flat you lie in the water also change drag, so two swimmers of equal weight can burn different amounts⁴.

Pool Laps, Distance and Water Temperature

Laps are hard to turn into calories. Pools differ in length, a lap can mean one length or two, and pace varies. For that reason this calculator uses time, not laps. The compendium does give freestyle speeds: 30 to 45 yards per minute for slow, about 50 for medium and about 75 for fast³. The pace helper compares your swim to those.

Cold water can raise the cost. In one review, oxygen use was higher in cold water than in warm water during moderate exercise, and shivering can lower efficiency⁵. This calculator assumes a normal pool, so a cold lake or sea swim may burn more than shown.