Our calorie calculator uses the Mifflin St. Jeor equation, an equation for estimating Basal Metabolic Rate (BMR).

The equation is as follows:

Where ‘s’ is a constant, +5 for males and −161 for females.

Once we have the BMR, we factor in your selected activity level and weight goal. If you select that you want to lose weight, we suggest a 20% calorie deficit, and if you want to gain, we suggest a 15% surplus. This is a conservative amount, and another popular method is to simply add or subtract 500 calories to your targets depending on your goals.