Calorie Deficit Calculator
Turning a Weight Loss Goal Into a Calorie Number
"Eat less" isn't a plan; a specific daily calorie target is. This calculator starts from the same Mifflin-St Jeor total daily energy expenditure used elsewhere on this site, then subtracts the daily deficit implied by a chosen weekly weight loss rate — converting a goal expressed in kilograms per week into a concrete number of calories to eat per day.
The Formula
Daily Deficit = (Weekly Weight Loss Goal × 7,700 kcal/kg) ÷ 7
Target Calories = TDEE − Daily Deficit
7,700 kilocalories is the commonly used approximation for the energy stored in one kilogram of body fat. Dividing the weekly deficit by 7 spreads it evenly across every day rather than concentrating it into occasional large cuts.
Worked Example
A 30-year-old man, 85 kg, 178 cm tall, moderately active: BMR = 1,817.5 kcal/day, TDEE = 1,817.5 × 1.55 = 2,817.1 kcal/day.
| Weekly goal | Daily deficit | Target calories |
|---|---|---|
| 0.25 kg/week | 275.0 kcal | 2,542.1 kcal/day |
| 0.5 kg/week | 550.0 kcal | 2,267.1 kcal/day |
| 0.75 kg/week | 825.0 kcal | 1,992.1 kcal/day |
| 1.0 kg/week | 1,100.0 kcal | 1,717.1 kcal/day |
Computed with the calculator's own formula. Doubling the weekly goal from 0.5 to 1.0 kg doubles the daily deficit, which is why aggressive rates push the target calorie figure down quickly.
The Built-In Safety Check
If the computed target falls below 1,500 kcal/day for men or 1,200 kcal/day for women — commonly cited floor figures below which sustained intake is generally not recommended without medical supervision — this calculator flags the result with a warning rather than presenting it as a straightforward answer.
How to Use This Calculator
- Choose Metric (kg/cm) or Imperial (lb/in) units.
- Select Male or Female for Sex.
- Enter your Age, Weight, and Height.
- Select your Activity level.
- Enter your Goal Weight Loss Rate in kg per week.
- Select Calculate for your TDEE, daily deficit, and target daily calories.
Related Calculations
For your maintenance calorie baseline without a deficit applied, see the Daily Calorie Needs Calculator. Once you have a target, the Macronutrient Ratio Calculator breaks it into protein, carb, and fat grams.