Calorie Deficit Calculator
Enter your current weight, target weight, and daily intake to see your weekly deficit or surplus and an estimated timeline to reach your goal.
Inputs
Results
Daily deficit / surplus
−400 kcal (deficit)
Weekly deficit / surplus
−2800 kcal (deficit)
Estimated weekly change
-0.36 kg/week
Estimated time to goal
14 weeks
Projected goal date
25 July 2026
Don't know your maintenance calories?
Calculate them with the Calorie Needs Calculator
Know your calorie target? Split it into macros.
Open the Macro Calculator
Disclaimer: This estimate assumes 1 kg of body weight change equals roughly 7,700 kcal. Real progress depends on water retention, muscle gain, metabolic adaptation, and tracking accuracy.
What is a calorie deficit?
A calorie deficit happens when you consume fewer calories than your body burns in a day. Over time, a sustained deficit leads to weight loss as the body draws on stored fat for energy. A surplus — eating more than you burn — leads to weight gain.
The standard rule of thumb is that 1 kg of body fat contains roughly 7,700 kcal. A daily deficit of 500 kcal produces about 0.45 kg of loss per week. In practice, real rate of change varies due to water retention, training effects, and metabolic adaptation.
How this calculator works
- It calculates your daily balance as the difference between your daily intake and your maintenance calories (TDEE).
- It multiplies the daily balance by 7 to get your weekly energy balance.
- It estimates weeks to goal by dividing the required energy change (weight difference × 7,700 kcal/kg) by your weekly balance.
- It adds the estimated weeks to today to project a goal date.
Tips for a sustainable deficit
- Track weekly weight averages rather than daily readings — daily fluctuations from water and food volume are normal.
- A deficit between 300 and 500 kcal per day is generally easier to sustain than larger cuts without muscle loss.
- Keep protein intake high during a deficit to preserve lean mass.
- If progress stalls for two to three weeks, reassess your actual intake and adjust rather than cutting further.
FAQ
How do I find my maintenance calories?
Use the Calorie Needs Calculator to estimate your TDEE from age, sex, weight, height, and activity level. That value is your maintenance number.
Is the 7,700 kcal per kg rule accurate?
It is a widely used approximation. Pure fat contains about 9 kcal per gram, but stored body fat also contains water and connective tissue. The real figure varies between 6,000 and 8,000 kcal per kg depending on the individual.
Why is my actual progress slower than the estimate?
Water retention, increased muscle mass, and metabolic adaptation all affect scale weight independent of fat change. Averages over two to four weeks are a more reliable indicator than week-to-week comparisons.
Can I use this calculator for weight gain?
Yes. Enter a target weight above your current weight and a daily intake above maintenance. The calculator will show your surplus and the estimated time to reach your goal.