Health Tools

The Mifflin-St Jeor equation (2005) is generally considered the most accurate for most people, with a margin of error of ±10%. The Katch-McArdle formula is more accurate if you know your exact body fat percentage, as it uses lean body mass. Harris-Benedict (revised 1984) is still widely used. Our calculator shows all three so you can compare.

General guideline is 35ml per kg of body weight. A 70kg person needs about 2.45 liters. However, this increases with physical activity (add 500ml per hour of exercise), hot/humid climate (add 300-500ml), and for breastfeeding women (add 700ml). Our calculator adjusts all these factors automatically.

BMR (Basal Metabolic Rate) is the calories your body needs at complete rest — just to keep organs functioning. TDEE (Total Daily Energy Expenditure) is BMR multiplied by your activity factor. If you're sedentary, TDEE = BMR × 1.2. Moderately active: BMR × 1.55. Very active: BMR × 1.9. TDEE is what you actually burn per day.

BMI is a useful screening tool but has limitations. It doesn't distinguish between muscle and fat, so athletes may have a high BMI despite being very healthy. It also doesn't account for where fat is distributed. For a complete picture, consider waist circumference, body fat percentage, and other metabolic markers alongside BMI.