Calorie Deficit Calculator

What this calculator estimates

A calorie deficit means consuming less energy than your body uses over time. This calculator starts with the Mifflin–St Jeor resting-energy equation, applies an activity factor, and then subtracts a selected planning deficit.

How to use the estimate

Treat the result as a starting range, not a prescription. Track your average body weight for two to four weeks under reasonably consistent conditions. If the trend is much faster, slower or less comfortable than expected, adjust gradually. Day-to-day scale changes mostly reflect water, food volume and normal measurement noise.

Why the result is a range

No online equation can directly measure your metabolism, movement efficiency, food-label error or adaptive changes. The displayed maintenance value is therefore an estimate. A smaller deficit is often easier to sustain and leaves more room for nutritious foods, training and recovery.

A practical example

Suppose an estimated maintenance level is 2,250 kcal. A 300-kcal planning deficit gives a target near 1,950 kcal. That does not guarantee a precise weekly loss. Use adherence, hunger, energy, workout performance and the multi-week trend together.

Safer expectations

The CDC describes gradual, steady loss—about 1 to 2 pounds per week—as more likely to be maintained than faster loss. A suitable pace may be slower, and some people should not intentionally pursue a deficit without professional care.

Frequently asked questions