Fitness Calculators
16 calculators built on established published formulas — Mifflin-St Jeor, Karvonen, Epley, the U.S. Navy method, and others. Every result updates as you type.
Body Composition
BMI Calculator
Estimate Body Mass Index from your height and weight.
BMI = weight (kg) / height (m)²
Body Fat Calculator
Estimate body fat percentage using circumference measurements.
U.S. Navy circumference method
Lean Body Mass Calculator
Estimate the weight of everything in your body that is not fat.
Boer formula
Ideal Weight Calculator
See weight ranges from several classic reference formulas.
Devine, Robinson, Miller, and Hamwi formulas
Pregnancy Weight Gain (Educational)
General reference ranges for weight gain in pregnancy, based on pre-pregnancy BMI.
Institute of Medicine reference ranges
Energy & Macros
BMR Calculator
Estimate the calories your body burns at complete rest.
Mifflin-St Jeor equation
TDEE Calculator
Estimate your Total Daily Energy Expenditure — maintenance calories.
Mifflin-St Jeor BMR × activity factor
Calorie Calculator
Work out daily calorie targets for your specific goal.
Mifflin-St Jeor with goal adjustment
Macro Calculator
Split your daily calories into protein, carbohydrates, and fat.
Calorie target split by macro ratio
Protein Intake Calculator
Estimate a daily protein range based on bodyweight and training goal.
Bodyweight × goal-based coefficient
Lifestyle
Performance
One Rep Max Calculator
Estimate your maximum single lift from a submaximal set.
Epley formula
Heart Rate Zone Calculator
Calculate your five training heart rate zones.
Karvonen method using heart rate reserve
VO₂ Max Estimator
Estimate aerobic capacity from a 12-minute run distance.
Cooper 12-minute test
Running Pace Calculator
Convert a distance and finish time into pace per kilometre.
Time ÷ distance