Fitness & Health Calculators
Body composition, energy needs and other health metrics.
These calculators turn a few measurements into the numbers clinicians and coaches tend to use. BMI is the quickest, needing only height and weight, but it cannot tell muscle from fat, which is why a very muscular person often reads as overweight on it. The body fat calculator uses circumference measurements instead and gives a more useful picture for anyone training seriously.
The calorie calculator estimates daily energy needs with the Mifflin-St Jeor equation, then adjusts for how active you are. It is the starting point for a deficit or a surplus rather than a target in itself: pick the goal, then adjust after a couple of weeks based on what actually happens.
None of this is medical advice. The formulas are population averages, and an individual can sit well outside them for reasons a calculator cannot see. Talk to a doctor before making significant changes, particularly if you have a health condition.