Calorie Deficit Calculator
Find the daily calorie deficit needed to reach your goal weight on schedule.
This tool is for informational and educational purposes only. It is not a substitute for professional financial, medical, legal, or engineering advice. See Terms of Service.
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A calorie deficit is the difference between the calories you consume and the calories you burn. Creating a sustained deficit is the mechanism behind all fat loss. This calculator tells you exactly how large that deficit needs to be to reach your goal weight in your chosen timeframe. Here is how to use it:
- Enter your current and goal weight. The calculator uses the difference to determine how much weight you need to lose.
- Enter the number of days. 90 days is 3 months. 180 days is 6 months. Choose a realistic timeline that gives you a sustainable daily deficit.
- Enter your TDEE. Use the TDEE Calculator to find this number. TDEE is your maintenance calorie level. The calculator subtracts your daily deficit from this to give your daily calorie target.
- Check the health indicator. If your deficit exceeds 1,000 calories per day (more than 2 lbs per week), the calculator flags it as potentially unsafe and suggests extending your timeline.
About Safe Rates of Weight Loss
One pound of body fat contains approximately 3,500 calories. One kilogram contains approximately 7,700 calories. These conversions let us calculate exactly how large a deficit is needed to lose a given amount of weight. A 500-calorie daily deficit creates a 3,500-calorie weekly deficit, which equals roughly 1 lb of fat loss per week under ideal conditions.
Most health organizations recommend a maximum rate of 1-2 lbs (0.5-1 kg) of weight loss per week for sustainable fat loss without significant muscle loss. A deficit larger than 1,000 calories per day can cause muscle tissue loss, nutrient deficiencies, fatigue, and metabolic adaptation. Slower, more moderate deficits tend to produce better long-term body composition outcomes because they preserve more lean mass.
Frequently Asked Questions
How many calories do I need to cut to lose 1 pound per week?
Since one pound of fat contains approximately 3,500 calories, you need a 3,500-calorie weekly deficit to lose 1 lb per week. This translates to a 500-calorie daily deficit. You can create this deficit through diet alone, exercise alone, or a combination of both. Most experts recommend combining both approaches for the best results, as cutting calories too aggressively can cause muscle loss and metabolic slowdown.
Is a 1,000-calorie deficit per day safe?
A 1,000-calorie daily deficit is at the upper boundary of what most guidelines consider acceptable, leading to approximately 2 lbs of weight loss per week. For most people, this is manageable for short periods, but it becomes harder to sustain and risks more muscle loss than smaller deficits. Very short or very tall individuals, or those with high or low TDEE, may have different tolerances. Any deficit larger than 1,000 calories per day should be done under medical supervision.
Will I lose weight faster if I skip meals?
Skipping meals can create a calorie deficit, but it often backfires by causing intense hunger that leads to overeating later. Meal timing matters far less than total daily calorie intake. Spreading meals throughout the day with adequate protein at each meal tends to reduce hunger, preserve muscle mass, and make adherence easier. Intermittent fasting can work for some people, but the benefit comes from the calorie reduction it enables, not from fasting itself.
Why is my weight loss slower than the calculator predicts?
Several factors can slow actual weight loss relative to predictions: water retention from high-sodium foods or hormonal changes, inaccurate calorie tracking (studies show most people underestimate intake by 20-30%), metabolic adaptation as the body adjusts to a deficit, and variation in TDEE estimates. The 3,500 cal/lb rule also assumes pure fat loss, while actual weight changes include water and muscle fluctuations. Weekly weigh-ins and a 4-6 week average give a more accurate picture than day-to-day numbers.