Fitness formulas

Convert inputs to kilograms and meters if needed, then divide mass by height squared.

US customary

w in pounds, h in inches. Same kg/m² scale.

Underweight

WHO adult cutoff (not for children).

Normal range

Often labeled “healthy weight” on adult charts.

Overweight

Screening band; muscle mass can raise BMI.

Obese (class I+)

Further classes exist; this sheet stops at the 30 cutoff.

Male: 10w + 6.25h − 5a + 5 (w in kg, h in cm, a in years).

Female: 10w + 6.25h − 5a − 161.

Logarithms of waist (− neck) and height feed a sex-specific formula.

Compute BMR (Mifflin–St Jeor), multiply by activity, then apply the goal offset.

Calories ≈ MET × weight (kg) × hours.

Enter Age and Max HR (0 = use 220−age) for the Heart Rate Zones Calculator; use finite values in the indicated domain. The calculator reports Max HR, Z2 low, Z2 high, Z4 low, and Z4 high: Zone bounds as fractions of maximum heart rate. The age-based maximum is approximate and can differ substantially between individuals.

Male: 50 kg + 2.3 kg per inch over 5 ft; female: 45.5 kg + 2.3 kg per inch.

Apply the sex-specific Boer coefficients to weight (kg) and height (cm).

Enter Calories, Protein %, Carb %, and Fat % for the Macro Split Calculator; enter percentage fields as percentage points. The calculator reports Protein g, Carbs g, and Fat g: Convert percent of calories to grams using 4/4/9 kcal per gram. This is a general estimate, not individualized medical or training advice.

Compute Mifflin–St Jeor BMR, then scale by activity.

Enter Weight lifted and Reps for the One Rep Max Calculator; use positive Weight lifted and a realistic whole-number Reps count. The calculator reports Estimated 1RM: Epley estimates max from a submax set. The estimate becomes less reliable for very high repetition counts or nonmaximal sets.

Convert elapsed time to minutes, then divide by distance.

Enter Pace (min/km) and Distance (km) for the Pace to Race Time Calculator; retain the units printed in each label. The calculator reports Time (minutes), Hours part, and Minutes remainder: Time = pace × distance. This is a general estimate, not individualized medical or training advice.

Enter Weight (kg) and g per kg for the Protein Target Calculator; retain the units printed in each label. The calculator reports Protein (g/day): Common planning uses a grams-per-kilogram factor. This is a general estimate, not individualized medical or training advice.