Caloric Deficit Calculator
Weight Loss Is Arithmetic Before It's Anything Else
Every weight-loss method eventually reduces to the same underlying equation: consuming fewer calories than the body burns. This calculator does that math directly — estimating total energy expenditure from Mifflin-St Jeor, then comparing it against the calories actually being eaten to produce a concrete deficit or surplus figure, rather than leaving "eat less" as a vague instruction.
The Formula
BMR (female) = 10 × Weight(kg) + 6.25 × Height(cm) − 5 × Age − 161
TDEE = BMR × Activity Factor
Caloric Deficit = TDEE − Calories Consumed
Converting Deficit to Weight Change
Weekly Change (kg) = (Daily Deficit × 7) ÷ 7700
These conversion factors come from the commonly cited energy density of body fat — roughly 3500 kcal per pound (7700 kcal per kg) — a widely used approximation rather than an exact figure for any individual, since real weight change also includes water and some lean tissue.
Reading Your Result
- A positive deficit means calories consumed are below TDEE — the trend points toward weight loss.
- A negative deficit (surplus) means calories consumed exceed TDEE — the trend points toward weight gain.
- Near zero indicates roughly weight-maintenance calorie intake.
How to Use This Calculator
- Select your gender.
- Enter your age, weight, and height (with unit selectors for weight and height).
- Select your activity level.
- Enter your current daily calorie consumption.
- Select Calculate to see your daily deficit or surplus and estimated weekly weight change.
Related Calculations
Get your baseline energy number from the TDEE Calculator, then plan protein intake with the Protein Calculator to protect lean mass during the deficit.