Fat loss needs a calorie deficit and muscle needs a surplus — but both start from knowing your daily burn. This calculator estimates your basal metabolic rate (what you burn at rest), multiplies by your activity level for total daily energy expenditure (TDEE), and shows three intake targets.
The formula
BMR uses the Mifflin-St Jeor equation, the most accurate general formula available: men: 10×weight(kg) + 6.25×height(cm) − 5×age + 5; women: same minus 161. TDEE = BMR × activity factor (1.2 sedentary, 1.375 light, 1.55 moderate, 1.725 very active, 1.9 extreme). Enter pounds and feet — conversion happens automatically.
How to use the numbers
Fat loss: eat 300–500 calories below TDEE — that yields roughly 0.5–1 lb of loss per week, sustainable and muscle-sparing. Maintain: eat at TDEE. Gain: 200–300 above TDEE with strength training. Never eat below your BMR for extended periods — aggressive cuts cost you muscle and metabolism, and the rebound is real.