BMI & Daily Calorie Calculator Online Free
Enter height, weight, age, sex and activity level to get BMI with WHO category labels, BMR via the Mifflin-St Jeor equation, TDEE and calorie targets for maintenance, fat loss or muscle gain — plus rough macro splits. Everything runs in your browser; no account, no upload of body measurements.
BMI & Daily Calorie Calculator In-Browser Workspace
Input data or select files to begin. 100% private, client-side execution with zero server transmission.
How to Use BMI & Daily Calorie Calculator
- Step 1: Pick units: metric (cm / kg) or imperial (ft-in / lb). Switching units converts the values you already typed.
- Step 2: Enter height, weight, age and select biological sex — used only for the BMR formula constant.
- Step 3: Choose an activity factor from sedentary (×1.2) through very active (×1.55–1.725) based on your training week.
- Step 4: Click Calculate to see BMI with category, BMR, TDEE and calorie targets for cut / maintain / gain.
- Step 5: Optionally adjust the calorie deficit or surplus percentage and review the optional macro ratio split.
About BMI & Daily Calorie Calculator
BMI is weight in kilograms divided by height in metres squared (kg/m²). WHO bands classify adults as underweight (<18.5), normal (18.5–24.9), overweight (25–29.9) and obese (≥30). BMI does not distinguish fat from muscle, so athletes and pregnant people should treat it as a screening number only. Basal Metabolic Rate uses Mifflin-St Jeor (1990), the equation generally preferred over Harris-Benedict in modern dietetics: BMR = 10×weight(kg) + 6.25×height(cm) − 5×age + s, where s is +5 for males and −161 for females. Total Daily Energy Expenditure multiplies BMR by an activity factor (1.2 sedentary … 1.725 very active, up to 1.9 athlete-level). Cut targets subtract a chosen percentage (default 20%) from TDEE; bulk targets add ~10%. Macro defaults of 30% protein / 40% carbs / 30% fat are a starting point, not medical advice — protein is often set at 1.6–2.2 g per kg body weight for training populations. Formulas are estimates; real needs vary with NEAT, thermic effect of food and metabolic adaptation.
Frequently Asked Questions
Is BMI accurate for athletes?
No. Muscle mass inflates BMI, so lean athletes can read “overweight” while carrying low body fat. Use waist circumference or body-composition methods alongside BMI.
Why Mifflin-St Jeor instead of Harris-Benedict?
Mifflin-St Jeor (1990) tends to predict resting energy more closely for modern adult samples; Harris-Benedict (1918/1984) often runs slightly higher.
Is a 20% calorie deficit safe?
Moderate deficits of 10–25% are common for fat loss, but medical conditions, pregnancy, underweight and eating-disorder history require a clinician’s guidance — this tool is not medical advice.
Does activity level get stored?
No. Height, weight and selections stay in page memory only; nothing is uploaded or saved on a server.
How often should I recalculate?
Re-run the calculator every 4–6 weeks or after a ~5 kg weight change so TDEE tracks your new mass.