How to Use
Enter your age, biological sex, weight, height, and activity level.
Click Calculate to see your TDEE (maintenance calories).
Review the deficit table: the 250 kcal/day deficit targets ~0.25 kg loss per week; the 500 kcal/day deficit targets ~0.5 kg per week.
Pick the deficit level that fits your timeline and feels sustainable - faster is not always better.
Set your daily calorie goal in a food tracking app (MyFitnessPal, Cronometer, etc.) and prioritize protein.
Re-run the calculator every 3–4 weeks as your weight changes to keep the deficit accurate.
What Is This Tool?
A calorie deficit occurs when you consume fewer calories than your Total Daily Energy Expenditure (TDEE), forcing your body to draw on stored energy - primarily body fat - to make up the shortfall. The widely cited rule that 3,500 calories equals one pound (about 0.45 kg) of fat loss is a useful approximation, but research shows the relationship is not perfectly linear: as you lose weight, your TDEE drops, your body adapts hormonally, and the rate of loss slows over time. For most adults, a moderate deficit of 250–500 kcal per day produces safe, sustainable fat loss of approximately 0.25–0.5 kg (0.5–1 lb) per week without triggering severe hunger or muscle loss. Protein intake becomes especially important during a deficit - eating at least 1.6–2.2 g of protein per kg of body weight helps preserve lean muscle mass while the body sheds fat.
Why It Matters
A calorie deficit that is too aggressive leads to muscle loss, fatigue, nutrient deficiencies, and rebound weight gain. A deficit that is too small yields frustratingly slow progress. Calculating your personal deficit based on your actual TDEE - rather than using a generic 1,200 kcal diet - protects your metabolic health and makes the process sustainable long-term.