Last updated October 10, 2026 · Report an error
A consistent daily calorie deficit (or surplus) translates into weight change over time at a fairly predictable rate — roughly 7,700 kcal per kilogram of body weight, a widely-cited approximation used across fitness and nutrition planning.
This calculator takes your current weight, target weight, and daily calorie deficit, and estimates how many days it'll take and what date you'll reach your goal.
How it works
Enter your current weight, target weight, and daily calorie deficit (or surplus, if gaining weight). The tool finds the total calories needed to reach your goal weight change, divides by your daily deficit, and adds that many days to today's date.
- Enter current weight (kg).
- Enter target weight (kg).
- Enter daily calorie deficit/surplus (kcal).
- Click Calculate to see your results.
Examples
Losing 5kg at a 500 kcal/day deficit
Going from 80kg to 75kg at a 500 kcal/day deficit takes an estimated 77 days.
Who should use it
- Setting a realistic timeline for a weight loss or weight gain goal.
- Comparing how different calorie deficit levels affect your estimated timeline.
Industry applications
- Fitness tracking and nutrition planning
Advantages
- Simple way to translate a calorie deficit goal into a concrete timeline.
- Uses a standard, widely-cited energy-to-weight conversion.
Limitations
- Assumes a perfectly linear, constant rate of change, which doesn't always match real-world results.
Common mistakes to avoid
- Assuming weight loss is perfectly linear — the body's response to a sustained deficit can change over time (metabolic adaptation).
- Using an extremely large calorie deficit expecting faster results, which is generally not sustainable or safe long-term.
Best practices
- Treat the estimated date as a rough target rather than a guarantee, and re-check your progress periodically rather than fixating on a single calculated date.
Tips
- Pair this with the TDEE Calculator to find your daily calorie needs first, then use the difference between that and your intake as your deficit here.