Calorie Deficit Calculator

How a Calorie Deficit Works

Weight loss is fundamentally about energy balance. When you consistently consume fewer calories than your body burns, it draws on stored body fat to make up the difference. This is a calorie deficit.

The key is finding a deficit that's sustainable — large enough to produce results, but small enough that you don't sacrifice muscle, energy, or long-term adherence.

Deficit Size Guidelines

Moderate

−300 to −500 cal/day

~0.5–1 lb/week

Recommended

Aggressive

−500 to −750 cal/day

~1–1.5 lb/week

Very Aggressive

−750 to −1000 cal/day

~1.5–2 lb/week

Risk of muscle loss

Frequently Asked Questions

What is a calorie deficit?

A calorie deficit means consuming fewer calories than your body burns (TDEE). This forces your body to use stored energy (body fat) to make up the difference, resulting in fat loss over time.

How large should my calorie deficit be?

A deficit of 300–500 calories per day is generally recommended for sustainable fat loss of 0.5–1 lb per week. Larger deficits can lead to muscle loss and metabolic adaptation.

How fast will I lose weight in a calorie deficit?

A deficit of 500 calories per day theoretically produces about 1 lb (0.45 kg) of fat loss per week (3,500 calories = 1 lb of fat). Actual results vary based on water retention, muscle mass changes, and metabolic adaptation.