GymGoal uses Compendium of Physical Activities (CPA) to estimate the amount of burned calories. CPA is maintained by Arizona State University. It lists physical activities with their MET values.

MET (Metabolic Equivalent) shows how much energy the activity burns, compared to the reference metabolic rate. 1 is roughly equivalent to sitting quietly. 2 means that the activity uses twice the amount of calories.

CPA lists standard MET values, but they need to be corrected for gender, body mass, height, and age. Using standard MET values would underestimates the amount of energy. For example standard MET for running at 6 mph is 9.8. However corrected MET is 12.3 for a 55 years old male with body weight 91 kg and height 178 cm. GymGoal shows and uses corrected MET values.

Some activities in CPA are variations of a base activity for different speeds. GymGoal groups such variations under the base activity. If you select the base activity, GymGoal will automatically use the proper speed variation. However the speed variations are also selectable. If you select a specific speed variation, GymGoal will use the selected MET value without any speed adjustment.