Your Total Daily Energy Expenditure (TDEE) is the total number of calories your body burns each day, accounting for your basal metabolism, physical activity, and the thermic effect of food. Knowing your TDEE is the essential first step for any weight-related goal. This free calculator uses the Mifflin-St Jeor equation — the most validated formula for estimating calorie needs in adults.
How the Calorie Calculator Works
The calculator runs two steps. First it computes your BMR (Basal Metabolic Rate) — the calories your body burns at complete rest — using the Mifflin-St Jeor formula: for men, BMR = (10 × kg) + (6.25 × cm) − (5 × age) + 5; for women, the same formula ending in −161. Then it multiplies your BMR by an activity factor (1.2 for sedentary up to 1.9 for extra active) to produce your TDEE. Subtract 500 cal/day from TDEE to lose ~1 lb/week; add 300–500 cal/day to gain lean muscle.
3 Real-World Examples
30-year-old woman, 5'5" (165 cm), 165 lbs (75 kg), moderately active. TDEE ≈ 2,180 calories/day. To lose 1 lb/week, create a 500-calorie daily deficit → eat 1,680 cal/day. To lose 2 lbs/week → eat 1,180 cal/day (the safe minimum for women).
25-year-old man, 5'11" (180 cm), 170 lbs (77 kg), very active (trains 5x/week). TDEE ≈ 3,100 calories/day. To gain muscle, eat at a 300–500 cal surplus → 3,400–3,600 cal/day with adequate protein (150–180 g/day).
After losing 30 lbs, TDEE drops because you're lighter and your body adapts. Always recalculate after every 15–20 lbs lost. A 180-lb person's TDEE is ~400 cal/day lower than the same person at 220 lbs.
Tips
- Recalculate your TDEE every 15–20 lbs of weight change — your calorie needs shift as your body composition changes.
- Pair any calorie deficit with 0.7–1 g of protein per lb of body weight to preserve lean muscle mass.
- Track actual food intake for 2–3 weeks and compare to your predicted TDEE; adjust by ±100–200 cal based on real results.
- Never drop below 1,200 cal/day (women) or 1,500 cal/day (men) without medical supervision to avoid metabolic adaptation.
Understanding Calorie Deficits and Surpluses
One pound of body fat contains roughly 3,500 calories. A consistent 500 cal/day deficit produces approximately 1 lb of fat loss per week — a sustainable, evidence-backed rate. Larger deficits speed up initial loss but increase muscle wasting and trigger metabolic slowdown. On the flip side, a modest 300–500 cal surplus combined with progressive strength training supports muscle growth without excessive fat gain. Food quality matters too: high-protein, high-fiber foods keep you fuller per calorie, making deficits easier to sustain over time.