Calorie Deficit Calculator

How a calorie deficit works

A calorie deficit means eating less than your TDEE, forcing your body to draw on stored energy (fat, and to some degree muscle) to make up the difference. The commonly cited 3,500-calorie-per-pound figure is an approximation, not an exact constant, but it's a reasonable planning tool.

Bigger deficits produce faster short-term loss but carry more risk of muscle loss, fatigue, and poor training performance. Most sports nutrition guidance favors a moderate deficit, especially for athletes still trying to train hard.

Don't have your TDEE handy? Get it from the TDEE calculator first.

Where these numbers come from

The formulas and default values in this calculator are based on:

• ~3,500 kcal per pound of body fat approximation (commonly used, though individual metabolic adaptation makes it imprecise over time)
• general sports nutrition guidance favoring moderate deficits for trained athletes

These are planning estimates for training purposes. Check with a coach, trainer, or physician before starting a new program or maxing out.