What is a safe calorie deficit?

A moderate deficit of 500 cal/day (~1 lb/week) is commonly recommended. This calculator enforces safety floors of 1,200 cal/day (female) and 1,500 cal/day (male).

How accurate is the 3,500 cal = 1 lb rule?

The 3,500 cal/lb approximation is a useful starting estimate, but actual weight change is non-linear due to metabolic adaptation. This calculator includes a progressive slowdown in its projection.

Should I eat back exercise calories?

This calculator accounts for exercise through the activity multiplier. Eating back additional exercise calories may reduce your deficit below the intended level.

Calorie Deficit Calculator

Name: Calorie Deficit Calculator
Author: Manish Kumar

What Is a Calorie Deficit?

A calorie deficit occurs when you consume fewer calories than your body uses (TDEE — Total Daily Energy Expenditure). This calculator estimates your TDEE using the Mifflin-St Jeor equation and applies your chosen deficit level to project a daily calorie target ^[1].

For a detailed BMR calculation, see our Mifflin-St Jeor Calculator or Daily Energy Requirements Calculator.

Deficit Levels Explained

Conservative (−250 cal/day): ~0.5 lb/week. Easiest to sustain, least muscle loss risk.
Moderate (−500 cal/day): ~1 lb/week. The most commonly recommended rate ^[2].
Aggressive (−750 cal/day): ~1.5 lb/week. Suitable for shorter periods with adequate protein.
Maximum (−1000 cal/day): ~2 lb/week. Highest risk of lean mass loss; higher protein intake essential.

Safety Floors

This calculator will never recommend below 1,200 cal/day for females or 1,500 cal/day for males, regardless of the deficit level selected. Very low calorie intakes can make it difficult to meet micronutrient needs and may not be sustainable.

For protein targets during a deficit, see our Protein Calculator. For overall body composition planning, check the Body Recomposition Calculator.

How to Use This Calculator

Enter your sex, age, height, and current weight
Enter your target weight
Select your activity level and preferred deficit amount
Click "Calculate Calorie Deficit" to see your target calories, macro split, and timeline

Frequently Asked Questions

Sources & References

Optimal Diet Strategies for Calorie Management. Koliaki C, et al.. Nutrients (2021)
Calorie Restriction and Metabolic Adaptation. Martins C, et al.. Clinical Nutrition (2022)
Exercise vs Calorie Deficit for Body Composition. Rizky A, et al.. ResearchGate (2024)

Manish Kumar

Certified Personal Trainer & Sports Nutritionist

NASM-CPTCertified Sports Nutritionist10+ Years Experience500+ Clients Coached

NASM-certified fitness and nutrition coach with over 10 years of hands-on experience helping people build strength, lose fat, and live healthier lives. Specializing in gym-based workouts with a strong focus on lifting technique, biomechanics, and practical exercise science. Through FitLifeRegime, sharing the tools, tips, and insights that have worked for hundreds of clients — helping you start your own fitness journey with confidence and clarity.

Learn more about Manish

NASM Certified

Certified Personal Trainer & Sports Nutritionist from the National Academy of Sports Medicine

Disclaimer: This calculator is for informational and personal awareness purposes only. Results are estimates based on published formulas and may not reflect your exact measurements or outcomes.