Weight Loss Calculator

One pound of body fat contains roughly 3,500 calories. To lose 1 lb per week, you need a daily calorie deficit of about 500 kcal below your Total Daily Energy Expenditure (TDEE). This can be achieved through diet, exercise, or a combination of both.

BMR (Basal Metabolic Rate) is the number of calories your body burns at complete rest to maintain basic functions like breathing and circulation. This calculator uses the Mifflin-St Jeor equation to estimate BMR, then multiplies it by an activity factor to get your TDEE — the true baseline for planning a calorie deficit.

Most health authorities recommend a maximum of 1–2 lbs per week for sustainable, safe weight loss. Losing more than 2 lbs per week can lead to muscle loss, nutritional deficiencies, and metabolic slowdown. Always consult a healthcare provider before pursuing aggressive deficits.

Activity level determines your TDEE — how many calories you actually burn in a day beyond just resting. A sedentary person and an athlete with identical height and weight can have TDEEs that differ by 800–1,200 kcal/day, which dramatically changes the calorie target needed to achieve a deficit.

Yes. As your weight decreases, your BMR and TDEE also decrease because a lighter body requires fewer calories to maintain. It's a good idea to recalculate your targets every 10–15 lbs lost to keep your plan accurate and avoid a weight loss plateau.

A calorie deficit occurs when you consume fewer calories than your body burns in a day. Your body then turns to stored fat for energy, gradually reducing body fat over time. The size of the deficit determines the rate of weight loss — a larger deficit means faster loss, but also greater health risks if too extreme.

The projected date is a mathematical estimate based on a consistent daily deficit. In reality, weight loss isn't perfectly linear — it can fluctuate due to water retention, hormonal changes, and metabolic adaptation. Use the date as a motivational target, not a guaranteed outcome, and reassess your plan every few weeks.

Eating below your BMR is generally not recommended without medical supervision. Very low-calorie diets can cause muscle wasting, nutrient deficiencies, fatigue, and hormonal disruption. A moderate deficit of 500–750 kcal below TDEE is both effective and safe for most healthy adults.