Calorie Deficit Calculator
Find your daily calorie target and how long to reach your goal weight
What is a Calorie Deficit?
A calorie deficit occurs when you consume fewer calories than your body burns in a day. Since your body needs energy to function, it turns to stored fat when food intake is insufficient. One pound of body fat contains approximately 3,500 calories, which means a daily deficit of 500 calories creates roughly one pound of fat loss per week.
This calculator finds your TDEE — the total calories you burn per day — then subtracts your chosen deficit to give you a precise daily calorie target. It also calculates how many weeks it will take to reach your goal weight at your chosen rate of loss.
How Big Should Your Deficit Be?
A deficit of 500 calories per day is widely considered the sweet spot for sustainable fat loss. It produces approximately one pound of loss per week while preserving muscle mass and energy levels. Larger deficits of 750 to 1000 calories per day produce faster results but increase the risk of muscle loss, metabolic adaptation, and nutrient deficiencies.
Deficits below 1200 calories per day for women or 1500 calories per day for men are generally not recommended without medical supervision. Extreme restriction often backfires by triggering hunger hormones, reducing activity levels, and slowing metabolism — making long-term maintenance much harder.
Why Your Deficit Changes Over Time
As you lose weight your TDEE decreases because a lighter body burns fewer calories. This means your initial calorie target will need to be recalculated as you progress. Recalculate every 10 to 15 pounds of weight loss to stay on track. The timeline this calculator provides assumes a constant deficit — in reality your progress may be slightly slower as you get closer to your goal weight.
Calorie Deficit Calculator — Frequently Asked Questions
What is a calorie deficit?
A calorie deficit occurs when you consume fewer calories than your body burns. When in a deficit, your body draws on stored fat for energy, resulting in fat loss over time.
How big should my calorie deficit be?
A deficit of 300–500 calories per day is recommended for sustainable fat loss of 0.5–1 lb per week. Deficits larger than 750–1000 calories per day increase the risk of muscle loss, nutritional deficiencies and metabolic adaptation.
How long will it take me to lose weight?
At a deficit of 500 calories per day, you can expect to lose approximately 1 lb per week, since 3,500 calories roughly equals one pound of fat. The calculator shows your projected timeline based on your specific deficit and goal weight.
What is the minimum safe calorie intake?
Most health authorities recommend a minimum of 1,200 calories per day for women and 1,500 calories per day for men to ensure adequate nutrient intake. Very low calorie diets below these thresholds should only be followed under medical supervision.