Calorie Deficit Calculator
Calculate your daily calorie deficit target and estimate how many weeks it will take to reach a target weight loss.
Gender
Age
Height
cm
Weight
Activity Level
Deficit Pace
Target weight loss
kg
Maintenance calories
2,585 kcal/day
Target deficit calories
2,035 kcal/day
Daily deficit
550 kcal
Time to lose 5kg
~10.0 weeks
How the Calorie Deficit Calculator Works
This calculator finds your maintenance calories (via the Mifflin-St Jeor equation and your activity level), then subtracts a daily deficit based on the weight-loss pace you choose. It also estimates how many weeks it'll take to reach a target weight loss, using the standard estimate that 1 kg of fat ≈ 7,700 kcal.
How to Use It
- Enter your age, gender, height, and weight.
- Select your activity level and how aggressive a deficit you want.
- Enter a target weight-loss amount to see a rough timeline.
Example
A moderately active person with 2,400 maintenance calories choosing a moderate 550 kcal/day deficit would eat around 1,850 calories/day, and take roughly 10 weeks to lose 5kg.
Common Use Cases
- Setting a realistic daily calorie target for fat loss.
- Estimating how long a weight-loss goal will realistically take.
- Comparing how a mild vs. aggressive deficit changes your timeline.
FAQs
What's a safe calorie deficit?
A deficit of 500–750 kcal/day (roughly 0.5–0.75 kg/week) is generally considered a sustainable pace for most people. Larger deficits can speed up short-term results but are harder to maintain and more likely to cause muscle loss and fatigue. This calculator is for general planning only and isn't a substitute for advice from a doctor or dietitian, especially for larger deficits.
Why 7,700 kcal per kg of fat?
One kilogram of body fat stores roughly 7,700 kilocalories of energy, so a cumulative deficit of that size corresponds to losing about 1 kg. It's a widely used estimate, though actual results vary with water weight, muscle changes, and individual metabolism.
Why shouldn't I go below 1,200 calories?
Very low calorie intakes can make it hard to get enough nutrients and are difficult to sustain, which is why this calculator caps its suggested target at a minimum of 1,200 kcal/day. Extreme deficits should only be attempted under medical supervision.