Discover exactly how many calories your body needs each day with our free online Calorie Calculator. This powerful tool uses the scientifically validated Mifflin-St Jeor equation — considered the most accurate formula for estimating resting metabolic rate — to calculate your Basal Metabolic Rate (BMR) and Total Daily Energy Expenditure (TDEE) based on your age, gender, weight, height, and physical activity level. Understanding your daily calorie needs is the foundation of any successful nutrition plan, whether your goal is weight loss, muscle gain, or weight maintenance. Our calculator provides three key calorie targets: a deficit for weight loss (500 calories below TDEE), maintenance calories to stay at your current weight, and a surplus for weight gain (500 calories above TDEE). The 500-calorie adjustment corresponds to approximately 0.45 kg (1 lb) of weight change per week, which is widely recommended by nutritionists as a safe and sustainable rate. The Mifflin-St Jeor equation was developed in 1990 and has been shown in multiple studies to be more accurate than older formulas like the Harris-Benedict equation (1919) and the Katch-McArdle formula. For men, the BMR formula is: BMR = (10 × weight in kg) + (6.25 × height in cm) − (5 × age in years) + 5. For women: BMR = (10 × weight in kg) + (6.25 × height in cm) − (5 × age in years) − 161. The BMR represents the number of calories your body burns at complete rest — the energy needed to maintain basic life functions like breathing, circulation, and cell production. To get your TDEE, the BMR is multiplied by an activity factor that reflects your daily physical activity level. Our tool offers five activity levels: Sedentary (little or no exercise, factor 1.2), Lightly Active (light exercise 1–3 days per week, factor 1.375), Moderately Active (moderate exercise 3–5 days per week, factor 1.55), Very Active (hard exercise 6–7 days per week, factor 1.725), and Extra Active (very hard exercise plus a physical job, factor 1.9). Choosing the correct activity level is crucial for accurate results — most people overestimate their activity, so when in doubt, choose a lower level. Calorie counting is one of the most evidence-based approaches to weight management. Studies published in the New England Journal of Medicine and the Journal of the American Medical Association have consistently shown that creating a caloric deficit leads to weight loss regardless of macronutrient composition. However, the quality of calories matters too — prioritizing whole foods, lean proteins, healthy fats, and complex carbohydrates supports overall health and makes it easier to maintain a deficit without feeling hungry. Our Calorie Calculator is perfect for a wide range of users. If you are starting a weight loss journey, knowing your TDEE helps you set a realistic calorie budget that creates a deficit without being overly restrictive. If you are trying to build muscle, eating at a slight surplus ensures your body has enough energy for muscle protein synthesis. If you are an athlete, understanding your energy expenditure helps optimize performance and recovery. And if you simply want to maintain your current weight, knowing your maintenance calories allows you to eat intuitively while staying on track. The tool also displays your BMR separately, which is useful for understanding how many calories your body needs at rest. This can be particularly eye-opening — most people are surprised to learn that the majority of their daily calories (60–75%) are burned just keeping their body alive, with physical activity accounting for only 15–30% of total expenditure. The remaining 10% comes from the thermic effect of food (the energy required to digest and absorb nutrients). All calculations are performed instantly in your browser with zero data transmission. No personal information is stored or shared. The tool is completely free, requires no sign-up, and works beautifully on any device. For the most comprehensive health assessment, use our Calorie Calculator alongside the BMI Calculator, Water Intake Calculator, and Ideal Weight Calculator — all available free on ConvertAI Hub.
Free, fast, and runs entirely in your browser — no signup, no upload to a server.