Free Online Calorie & Nutrition Calculators

Calories are the fundamental unit of energy that fuels every process in your body — from breathing and circulating blood to exercising and thinking. Understanding how many calories your body needs each day is the cornerstone of effective nutrition planning, whether your goal is weight loss, muscle gain, or maintaining a healthy weight.

Your daily calorie needs are determined by two primary factors: your Basal Metabolic Rate (BMR) and your activity level. BMR represents the number of calories your body burns at complete rest — just to keep your organs functioning, your heart beating, and your lungs breathing. This typically accounts for 60-75% of your total daily energy expenditure.

When you add physical activity on top of your BMR, you get your Total Daily Energy Expenditure (TDEE). This is the total number of calories you burn in a day, and it's the number you need to know to manage your weight effectively. Eat fewer calories than your TDEE to lose weight, eat more to gain weight, or match it to maintain your current weight.

Our calculators use scientifically validated formulas trusted by nutritionists and healthcare professionals worldwide. The Mifflin-St Jeor equation, developed in 1990, is considered the most accurate for estimating BMR in most populations. The Harris-Benedict equation, revised in 1984, provides a reliable comparison. For those who know their body fat percentage, the Katch-McArdle formula offers the most precise estimate by factoring in lean body mass.

Beyond calories, macronutrients — protein, carbohydrates, and fat — play crucial roles in body composition, energy levels, and overall health. Protein supports muscle repair and growth (4 calories per gram), carbohydrates provide quick energy for your brain and muscles (4 calories per gram), and dietary fat supports hormone production and nutrient absorption (9 calories per gram).

All our tools run entirely in your browser — your personal data is never sent to any server. Use our suite of calculators to build a complete picture of your nutritional needs and take control of your health journey with science-backed precision.