Daily Calorie Needs Calculator
Understanding how many calories you need each day is the foundation of any nutrition plan, whether your goal is to lose fat, build muscle, or simply maintain your current weight. This calculator combines two well-established methods: the Mifflin-St Jeor equation for estimating your Basal Metabolic Rate (BMR), which is the calories your body burns at complete rest, and the Harris-Benedict activity multipliers, which scale that figure up based on how physically active you are. The five activity levels range from sedentary (a desk job with little deliberate exercise) to extra active (a physically demanding job or twice-daily training sessions). The result is your Total Daily Energy Expenditure (TDEE), the number of calories needed to maintain your current weight. The calculator also shows a weight loss target (TDEE minus 500 kcal per day, producing roughly 0.45 kg of loss per week) and a muscle gain target (TDEE plus 500 kcal per day). Use these as starting points and adjust based on real-world results over 2 to 4 weeks.
Formula
BMR (male) = 10*weight(kg) + 6.25*height(cm) - 5*age + 5
BMR (female) = 10*weight(kg) + 6.25*height(cm) - 5*age - 161
TDEE = BMR * activity factor
Weight loss = TDEE - 500 kcal/day
Muscle gain = TDEE + 500 kcal/day
Daily Calorie Needs Calculator: frequently asked questions
What is TDEE and how is it different from BMR?
Basal Metabolic Rate (BMR) is the calories your body burns at complete rest to keep vital organs functioning. Total Daily Energy Expenditure (TDEE) is your BMR multiplied by an activity factor that accounts for the extra calories burned through daily movement and exercise. TDEE is the number of calories you need each day to maintain your current weight.
What are the activity factors used in this calculator?
This calculator uses the Harris-Benedict activity factors: Sedentary (desk job, little exercise) = BMR * 1.2. Lightly active (light exercise 1-3 days/week) = BMR * 1.375. Moderately active (moderate exercise 3-5 days/week) = BMR * 1.55. Very active (hard exercise 6-7 days/week) = BMR * 1.725. Extra active (very hard exercise, physical job, or twice-daily training) = BMR * 1.9.
How many calories should I eat to lose weight?
Eating 500 calories per day below your TDEE creates a weekly deficit of 3,500 calories, which is roughly equivalent to 0.45 kg (1 lb) of fat loss per week. This calculator shows your TDEE minus 500 as your weight loss target. A deficit of 500 to 1,000 calories per day is generally considered safe for most healthy adults.
How many calories should I eat to build muscle?
Eating 500 calories per day above your TDEE creates a caloric surplus for muscle growth. Not all of this surplus will become muscle: without resistance training, much of it may be stored as fat. Combine a modest surplus with regular strength training and adequate protein (1.6 to 2.2 g/kg) for the most efficient muscle gain.
Should I recalculate as I lose weight?
Yes. As your body weight decreases, your BMR decreases because there is less mass to maintain. If you do not recalculate, the same calorie intake produces a progressively smaller deficit. Recalculate your TDEE every 5 to 10 kg of weight change or every 4 to 6 weeks to keep your targets accurate.
Official sources
- Mifflin MD, et al. (1990). "A new predictive equation for resting energy expenditure in healthy individuals." American Journal of Clinical Nutrition, 51(2):241-247.
- CDC: Balancing Calories
Reviewed by the CalculatorHub team, edited by James Graham, 14 June 2026. See our methodology.