Health & Fitness formules
BMI, BMR, TDEE, heart rate zones, and nutrition formulas.
Body Mass Index (BMI)
BMI = weight(kg) / height(m)²
A screening tool that uses height and weight to estimate body fat. Categories: Underweight (<18.5), Normal (18.5–24.9), Overweight (25–29.9), Obese (30+). BMI does not measure body fat directly and may not be accurate for athletes or elderly.
Basal Metabolic Rate (Mifflin-St Jeor)
BMR = 10×weight(kg) + 6.25×height(cm) - 5×age + s
Estimates the number of calories your body burns at rest to maintain basic life functions (breathing, circulation, cell production). This is your baseline — you burn more than this each day through activity.
Total Daily Energy Expenditure (TDEE)
TDEE = BMR × Activity Factor
Estimates total daily calories burned by multiplying BMR by an activity level multiplier. Sedentary (×1.2), Light (×1.375), Moderate (×1.55), Active (×1.725), Very Active (×1.9).
Maximum Heart Rate Formula
HRmax = 220 - age
A simple estimate of the highest heart rate an individual can achieve during maximal exercise. Used to set training heart rate zones.
Karvonen Heart Rate Formula
THR = (HRmax - HRrest) × %intensity + HRrest
Calculates target heart rate for a specific training intensity using heart rate reserve (HRR). More personalized than simple percentage of max HR because it accounts for resting heart rate.
Body Fat Percentage (Navy Method)
BF% = 86.010×log10(waist-neck) - 70.041×log10(height) + 36.76
Estimates body fat percentage using circumference measurements. The formula shown is for males — the female version also includes hip circumference.
One Rep Max (Epley Formula)
1RM = weight × (1 + reps/30)
Estimates the maximum weight you could lift for a single repetition based on a submaximal lift. Most accurate when reps are between 2 and 10.
Calorie Deficit for Weight Loss
Deficit = TDEE - Calorie Intake
To lose weight, consume fewer calories than you burn. A deficit of ~3,500 calories equals roughly 1 pound of fat loss. A 500 cal/day deficit targets ~1 lb/week loss.