Calorie Deficit Calculator

A calorie deficit happens when you consume fewer calories than your body uses. Over time, this gap pushes the body to use stored energy, which leads to gradual weight loss. The size of the deficit determines how quickly weight comes off.

A common safe range is 0.5 to 1 percent of body weight per week, which usually corresponds to a daily deficit of about 300 to 750 calories for most adults. Aggressive deficits (over 1,000 cal/day or daily intake below 1,200 cal) are harder to sustain and may need clinical supervision.

The planning estimate that one pound of body fat equals about 3,500 calories (one kilogram about 7,700 calories) is a starting approximation. Real weight loss is non-linear: metabolism adapts, water shifts, and hormones respond, so actual loss often differs from the linear estimate. Use it as a planning tool, not a guarantee.

Use the TDEE calculator on this site to estimate it from sex, age, height, weight, and activity. TDEE is the daily calorie level that keeps your weight stable. Subtract your deficit from TDEE to get a daily intake target.

By-date mode takes a target date and works out the daily deficit you would need to reach the target weight by then. By-rate mode lets you pick a weekly loss rate (such as 1 lb/week) and the calculator tells you how many days it will take.

Rapid loss can be appropriate in some clinical situations but generally is not recommended without supervision. Common downsides include muscle loss, low energy, nutrient gaps, and hormonal changes. For long-term success, moderate deficits with adequate protein and strength training tend to do better.