Free Nutrition Calculators Online
Estimate daily caloric needs, macronutrient ratios, and meal planning.
Nutrition planning starts with knowing how many calories your body actually needs. Our Calorie Calculator uses the Mifflin-St Jeor equation — widely regarded as the most accurate resting metabolic rate formula — to estimate your Basal Metabolic Rate (BMR) and Total Daily Energy Expenditure (TDEE). Enter your age, sex, height, weight, and activity level to get personalized calorie targets for weight loss, maintenance, or muscle gain. This single tool provides the foundation for any evidence-based diet or meal plan.
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The Science Behind Calorie Calculation
Your body burns calories constantly — even at rest — to fuel breathing, circulation, cell repair, and brain function. This baseline burn is your Basal Metabolic Rate (BMR). Multiply BMR by an activity factor to get your Total Daily Energy Expenditure (TDEE), the number you need to maintain your current weight.
Calorie Calculator
Our calculator applies the Mifflin-St Jeor equation, shown by research to be within 10% of measured metabolic rate for most adults. It factors in age, sex, height, weight, and activity level to produce three targets: a calorie deficit for weight loss, maintenance calories, and a surplus for muscle gain.
Applying Your Results
A 500-calorie daily deficit produces roughly one pound of fat loss per week. A 250"“500 calorie surplus supports muscle growth with resistance training. Monitor progress and adjust every 2"“4 weeks as your body adapts.
Metabolic Rate Essentials
- BMR — Calories burned at complete rest, accounting for 60"“75% of total daily expenditure.
- TDEE — BMR multiplied by an activity factor (1.2 for sedentary up to 1.9 for very active).
- Thermic Effect of Food — About 10% of intake is burned during digestion, with protein requiring the most energy.
- NEAT — Non-exercise activity thermogenesis varies dramatically between individuals and impacts total burn significantly.
Frequently Asked Questions
It is the most widely recommended formula for estimating Basal Metabolic Rate. For men: BMR = (10 × weight in kg) + (6.25 × height in cm) − (5 × age) + 5. For women: BMR = (10 × weight in kg) + (6.25 × height in cm) − (5 × age) − 161. Our Calorie Calculator applies this formula automatically using your inputs.
Most health authorities recommend a deficit of 500—750 calories below your TDEE for safe, sustainable weight loss of 1—1.5 pounds per week. Avoid going below 1,200 calories per day for women or 1,500 for men without medical supervision, as this can trigger metabolic adaptation and nutrient deficiencies.
Activity can nearly double your daily calorie requirement. A sedentary 170-pound man might burn 2,000 calories per day, while the same man with an intense exercise schedule could burn 3,500. Selecting the correct activity level in our Calorie Calculator ensures your targets reflect your actual energy expenditure.
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