What is a calorie deficit?
A deficit means average energy intake is below expenditure over time. The arithmetic is straightforward, but accurately estimating both sides and maintaining adequate nutrition requires more than a formula.
How the deficit is calculated
The tool estimates TDEE from Mifflin–St Jeor and activity, then applies your selected 5–25% reduction. The result shows estimated daily intake and the energy gap; it does not predict a weekly weight change.
How to use this calculator
- 1Enter measurements and choose your typical activity level.
- 2Select a deficit percentage to explore.
- 3Compare the energy gap and intake estimate, including any suitability warnings.
Understanding your result
A larger percentage produces a larger calculated gap, but does not establish that the target is suitable. The tool's intake boundaries are guardrails, not proof of adequate nutrition or individual safety.
Assumptions & limitations
- TDEE changes over time; a constant deficit cannot predict an exact rate of weight loss.
- Do not use this tool for underweight goals, pregnancy, breastfeeding, or eating-disorder recovery.
Frequently asked questions
Is a 500-calorie deficit right for everyone?+
No. The same absolute deficit represents a very different share of a small versus large energy budget. Health, nutrition, activity, and preferences matter.
Can exercise create part of a deficit?+
Activity contributes to expenditure. If your selected activity factor already includes it, adding the same estimated workout calories again would double-count it.
Why can scale weight stay flat during a deficit?+
Water, glycogen, food in the digestive tract, and measurement variation can mask short-term changes. The calculated deficit may also differ from the actual one.
Why might the calculator reject an intake?+
The tool restricts aggressive or low-intake scenarios. Passing those limits still does not establish that a calorie level meets your individual nutrition needs.
