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Swimming energy cost is calculated using MET values from the Compendium of Physical Activities, multiplied by body weight in kg and duration in hours.
Calories = MET × Weight (kg) × Duration (hr)Freestyle at moderate effort is MET 8.0; breaststroke at general effort is MET 10.3; backstroke moderate is MET 7.0; butterfly vigorous is MET 13.8. Higher MET reflects greater drag and muscle recruitment.
Breaststroke MET 10.3 | Freestyle moderate MET 8.0Leisure swimming (MET 6.0) vs vigorous lap swimming (MET 9.8–10.3) can differ by 60% or more. Match intensity to actual effort — continuous lap swimming with short rest burns more than casual recreational swimming.
Vigorous laps MET 9.8 vs leisurely MET 6.0Updated: July 2026
Steady lap swimming in a 25 m pool at ~2:00/100 m pace with 10 s rest between lengths.
→ ~420 kcal
Masters swim session using primarily breaststroke at moderate-to-vigorous effort.
→ ~670 kcal
Light recovery session after a long run, mixing strokes at low intensity.
→ ~240 kcal
Swimming MET values are generally higher than equivalent running paces because water resistance and thermoregulation increase energy cost. Do not substitute running compendium values.
If you rest significantly between sets, use average session intensity rather than peak lap intensity. A 60-minute session with 15 minutes of rest burns less than 60 minutes of continuous swimming.
Cold open water (below 20°C) increases thermogenic calorie cost by 10–20% beyond MET estimates. Pool swimming at 27–28°C has lower thermoregulatory demand than cold lake or ocean swims.
Swimming calorie burn varies widely by stroke, intensity, and technique efficiency. This calculator uses Compendium of Physical Activities MET values for different swim styles, scaled to your body weight and session duration to estimate energy expenditure in the pool.