Calorie Deficit Calculator
Explore a modest calorie reduction from maintenance, with clear limits and no promised weight loss.
Your estimate
Enter your values and calculate. Results will appear here.
The output is a subtraction scenario, not a prescribed diet. If the maintenance assumption is wrong by 250 kcal, the actual energy balance may differ by the entire selected deficit.
How to use this calculator
Start with a maintenance estimate, such as the result from the daily calorie calculator. Enter a modest reduction in kcal per day, not a percentage. Compare the intake and percentage reduction together.
Formula and methodology
Illustrative intake = maintenance kcal/day − selected deficit kcal/day.
Worked example
At maintenance of 2,400 kcal/day, subtracting 250 gives 2,150 kcal/day. The reduction is 250 ÷ 2,400 × 100 = 10.4%. Changing maintenance to 2,600 while keeping the same deficit gives 2,350, not a larger deficit.
What the result means
The output is a subtraction scenario, not a prescribed diet. If the maintenance assumption is wrong by 250 kcal, the actual energy balance may differ by the entire selected deficit.
Limitations
This interface permits 100–500 kcal/day, no more than 20% of maintenance, and no target below 1,600 kcal/day. These intentionally conservative software limits are not medical thresholds and do not prove a target is suitable. Nutritional adequacy requires more than a calorie total.
Common mistakes
Do not subtract the deficit twice or count an exercise estimate twice. Maintenance estimates already include an activity assumption. A single day on the scale cannot confirm the implied deficit.
Frequently asked questions
Why is my requested deficit rejected?
It exceeds the tool’s conservative range, percentage cap or intake floor. Rejection does not offer a substitute clinical target.
Will this produce a fixed weekly loss?
No. The calculation does not model water changes, adaptations or adherence and makes no weekly promise.