Calorie Deficit Calculator
Daily deficit from TDEE and target intake, with estimated weekly weight change.
Inputs
This calculator gives a general estimate and isn't medical advice. It doesn't account for your individual health history — talk to a doctor before making decisions based on it.
Formula
Deficit = TDEE − target intake · Weekly loss (kg) ≈ (deficit × 7) ÷ 7,700
Total daily energy expenditure minus what you plan to eat gives the calorie gap. Roughly 7,700 kcal corresponds to one kilogram of body fat, so multiplying the daily deficit by seven and dividing by 7,700 estimates weekly weight change.
Worked example
Maintenance at 2,500 kcal/day with a 2,000 kcal target creates a 500 kcal/day deficit — about 3,500 kcal per week, or roughly 0.45 kg (1 lb) of fat loss if intake and expenditure estimates hold.
Where this can give the wrong answer
- The 7,700 kcal/kg rule is a population average — water, glycogen, and muscle changes make short-term scale movement noisier than the math suggests.
- Very large deficits (above ~1,000 kcal/day) may trigger adaptive thermogenesis and aren't sustainable without medical supervision.
- TDEE drops as you lose weight; recalculate every few weeks rather than holding one deficit number for months.
FAQ
- Use the BMR calculator for resting burn, then the TDEE calculator to apply an activity multiplier. You can also enter a TDEE you already track from a food diary and scale.