How many calories you burn in 20 minutes of circuit training depends on what kind of circuit workout you do. Fitness coach Ben Cohn reports that there are two popular kinds of circuit workout: aerobic and resistance.
Aerobic Circuit Workout
According to information at fitness resource website HealthStatus, a 150-lb. athlete doing an aerobic calisthenics circuit routine will burn 102 calories in 20 minutes of moderate effort, or 183 calories in 20 minutes of vigorous effort.
Resistance Circuit Workout
That same person doing a moderate weight lifting circuit will burn 78 calories in 20 minutes of moderate effort, or 138 calories in 20 minutes of vigorous weight lifting.
How much you weigh affects how many calories you burn in any given activity. A 180-lb. person exercising vigorously would burn 40 more calories in 20 minutes of aerobic circuit training than a 150-lb. person, and 30 more calories at weight lifting. A lighter person would burn fewer calories in every exercise.