Swimming Calorie Calculator
Estimate how many calories you burn swimming, from treading water to fast freestyle and butterfly, based on your weight, your stroke and effort, and your time in the water.
How the swimming calorie calculator works
Swimming burn is estimated with METs, or metabolic equivalents. One MET is roughly the energy you use sitting still, so slow freestyle at 5.8 METs costs almost six times as much per minute. The calculator takes the MET value for your stroke and effort from the 2024 Adult Compendium of Physical Activities and scales it by your body weight and your time.
The formula and the strokes
Calories per minute equal METs times 3.5 times your weight in kilograms, divided by 200. The options match our swimming guide: treading water at moderate effort is 3.5 METs, recreational backstroke is 4.8, recreational breaststroke is 5.3, slow freestyle laps are 5.8, leisurely swimming is 6.0, training backstroke is 9.5, fast freestyle laps are 9.8, training breaststroke is 10.3, and butterfly is 13.8.
Why it is an estimate
Stroke technique changes the energy cost of swimming more than in most sports, and rest at the wall lowers the average for a whole session. MET values are group averages, so treat the result as a ballpark. Enter the minutes you actually spend swimming, not your total time at the pool.
Frequently asked questions
How many calories does 30 minutes of swimming burn?
For a 70 kg (155-pound) swimmer, about 130 calories treading water, about 175 for recreational backstroke, about 215 for slow freestyle laps, about 360 for fast freestyle, and about 505 for butterfly. Heavier swimmers burn more at the same effort.
Which swimming stroke burns the most calories?
Butterfly, by a wide margin, at 13.8 METs. Most people cannot hold it for long, so it rarely dominates a real session. Among strokes you can sustain, fast freestyle (9.8 METs) and training-pace breaststroke (10.3 METs) burn the most.
Does swimming burn more calories than running?
Usually not, at matched effort and time. Fast freestyle is 9.8 METs, a shade above running at 6 mph (9.3 METs), and running pulls ahead quickly at faster paces. Swimming's advantage is that the water supports your body weight, so you can train hard and often with far less joint loading.
Does treading water burn calories?
Yes. Treading water at a moderate effort is rated at 3.5 METs, similar to a steady walk, and treading fast and vigorously reaches 9.8 METs, the same as fast freestyle laps.
Is swimming good for weight loss?
It can be, as part of a calorie deficit. Swimming's strength is adherence: it is low impact, so you can train often without the joint stress that makes running hard to keep up. As with any exercise, most of the loss comes from diet, with swimming as support.