Calorie Deficit Calculator

A calorie deficit occurs when you consume fewer calories than your body burns in a day. Your body then draws on stored fat for energy, leading to weight loss over time. For example, a 500 kcal daily deficit typically results in about 1 pound of fat loss per week.

In theory, yes — one pound of fat contains roughly 3,500 calories, so a 500 kcal/day deficit adds up to 3,500 kcal per week, equalling about 1 lb of fat loss. In practice, actual weight loss can vary due to water retention, muscle mass changes, and metabolic adaptation, but this remains a solid and widely-used guideline.

Most health professionals recommend no more than a 1,000 kcal/day deficit, which corresponds to about 2 lbs of weight loss per week. Going below around 1,200 kcal/day for women or 1,500 kcal/day for men can deprive your body of essential nutrients and slow your metabolism. A moderate deficit of 500 kcal/day is generally the safest and most sustainable approach.

TDEE stands for Total Daily Energy Expenditure — the total number of calories you burn in a day, including all activity. It's calculated by first estimating your Basal Metabolic Rate (BMR) using the Mifflin-St Jeor equation, then multiplying by an activity factor based on how active you are. Your recommended calorie intake is simply your TDEE minus your chosen daily deficit.

BMR (Basal Metabolic Rate) is the number of calories your body needs at complete rest just to maintain vital functions like breathing and circulation. TDEE builds on this by adding calories burned through daily activities and exercise. Most people's TDEE is 20–70% higher than their BMR depending on activity level.

A safe starting point is to subtract 500 calories from your TDEE. This creates a moderate deficit without depriving your body of nutrients. Aim to stay above 1,200 kcal/day (women) or 1,500 kcal/day (men) at minimum. Combine your reduced intake with regular physical activity for best results.

Yes — when you select your activity level, the calculator multiplies your BMR by the corresponding activity factor to estimate your TDEE. The activity levels range from sedentary (factor ≈1.2) to extra active (factor ≈1.9), so choosing the right level is important for an accurate result.

Yes. As you lose weight, your BMR decreases because a lighter body requires fewer calories to sustain itself. This is why weight loss can plateau over time — your TDEE drops as you get lighter. It's recommended to recalculate your calorie target every 5–10 lbs of weight lost to keep making progress.