General health calculators are mostly linked to lifestyles. The commonly used ones are related to weight. You can calculate your body mass index (BMI for short), amount of calories burned during a work-out, or calories ingested with certain meals. You can also calculate how much of your body is actually fat, how much you need to eat daily to maintain health, how much alcohol gets into your blood during a drinking spell, or how much physical activity is needed to raise your heart rate to a certain level.