📉 Calorie Deficit Calculator
Enter how much weight you want to lose and over how many weeks to get the daily calorie deficit required.
Daily deficit needed
550 kcal
Weekly loss rate
0.5 kg/wk
Total deficit
38,500 kcal
Based on roughly 7,700 kcal per kg (3,500 per lb) of body fat: total deficit = weight × that figure, spread over your timeframe. Subtract the daily deficit from your maintenance calories (TDEE) to set your intake. This is a simplified estimate — real loss varies with water, muscle and metabolic adaptation. Not medical advice; consult a professional for a plan. 🔒 In your browser.
How the calorie deficit calculator works
Losing body fat means eating fewer calories than you burn — a deficit. A kilogram of body fat stores roughly 7,700 kcal (a pound about 3,500), so the total deficit to lose your target weight is that figure times the weight. Spread over your chosen number of weeks, that gives the daily deficit to subtract from your maintenance calories (your TDEE). The tool also shows the implied weekly loss rate and flags targets that are unusually aggressive.
This is a simplified model. Real weight change also reflects water, glycogen and muscle, and the body adapts by lowering its energy use as you lose weight, so progress often slows. A sustainable rate is about 0.5–1 kg (1–2 lb) per week; very large deficits are hard to keep up and risk losing muscle. This is educational, not medical or dietary advice — consult a professional for a plan.
Frequently asked questions
How do I calculate a calorie deficit?
Multiply the weight you want to lose by about 7,700 kcal per kg (3,500 per lb) for the total deficit, then divide by the number of days. Losing 5 kg in 10 weeks needs about a 550-kcal daily deficit.
How big should my calorie deficit be?
A common guideline is a 500-kcal daily deficit for roughly 0.5 kg (1 lb) of loss per week. Larger deficits lose weight faster but are harder to sustain and can cost muscle; going below your BMR long-term is not advised.
How many calories are in a kilogram of fat?
Roughly 7,700 kcal per kilogram (about 3,500 per pound). This estimate is the basis for deficit calculations, though the real figure varies a little and the body's response isn't perfectly linear.
How do I use the daily deficit?
Subtract it from your maintenance calories (TDEE — the calories that keep your weight stable). If your TDEE is 2,400 and you need a 550 deficit, aim for about 1,850 kcal a day, through eating less, moving more, or both.
Why is my weight loss slower than the calculator predicts?
The model is simplified. Water and glycogen shifts mask fat loss day to day, and as you get lighter your body burns fewer calories (metabolic adaptation), so the same intake becomes a smaller deficit. Adjust as you go.