Calorie Deficit Calculator
Set a safe calorie deficit and see how many weeks it takes to reach your goal weight.
About the Calorie Deficit Calculator
Most guidelines suggest losing 0.5 to 1 kg (1 to 2 lb) a week. The plan subtracts a daily deficit from your maintenance calories, using about 7,700 kcal per kilogram of fat lost.
Real weight loss slows as you go, because a smaller body burns fewer calories. Recalculate every few kilograms.
The formula
Daily deficit = weekly loss (kg) × 7,700 ÷ 7
- Maintenance
- BMR (Mifflin-St Jeor) × activity factor
- Weeks
- weight difference ÷ weekly rate
Worked example
A 40-year-old man, 180 cm and 82 kg, moderately active, aiming for 75 kg at 0.5 kg a week
- Maintenance (Mifflin-St Jeor × 1.55): (10 × 82 + 6.25 × 180 − 5 × 40 + 5) × 1.55 = 2,713 kcal
- Daily deficit: 0.5 × 7,700 ÷ 7 = 550 kcal
- Eat about 2,713 − 550 = 2,163 kcal a day; 7 kg takes about 14 weeks
Things to keep in mind
- This is an estimate for general information, not medical advice. Talk to a doctor or other qualified professional about your health.
- The 7,700 kcal/kg rule is a simplification; the NIH Body Weight Planner models adaptation more precisely.
Questions people ask
Is losing 1 kg a week safe?
For people with more weight to lose it can be, but 0.5 kg a week is easier to sustain and protects muscle.
Why did my weight stall?
Water shifts hide fat loss for a week or two, and maintenance calories drop as you lose weight.