Calorie Calculator

Calorie Calculator: Your Complete Guide to Daily Nutrition

Understanding your daily calorie needs is fundamental to any nutrition or fitness goal—whether you're trying to lose weight, build muscle, or maintain your current physique. Our comprehensive calorie calculator uses the scientifically-validated Mifflin-St Jeor equation to calculate your Basal Metabolic Rate (BMR), then factors in your activity level to determine your Total Daily Energy Expenditure (TDEE). From there, you can set personalized targets for weight loss, maintenance, or gain, complete with detailed macronutrient breakdowns.

Premium users gain access to our food database powered by Open Food Facts, allowing you to search over 2 million foods and track your daily intake. For related health calculations, see our BMI Calculator and Percentage Calculator.

Understanding BMR, TDEE, and Calorie Targets

Basal Metabolic Rate (BMR) is the number of calories your body burns at complete rest—just to maintain vital functions like breathing, circulation, and cell production. BMR typically accounts for 60-75% of daily calorie expenditure, depending on body composition and activity level.

Total Daily Energy Expenditure (TDEE) is your BMR multiplied by an activity factor. A sedentary office worker might multiply by 1.2, while a construction worker or athlete might multiply by 1.9 or higher. TDEE represents the total calories you burn in a day, including all movement and exercise.

Calorie targets are set relative to TDEE. To lose weight, eat 500 calories below TDEE (approximately 1 lb/week loss). To gain weight, eat 500 above TDEE. These 500-calorie adjustments are generally considered safe and sustainable. More aggressive deficits can work short-term but risk muscle loss and metabolic adaptation. Use our Savings Calculator for financial planning.

The Mifflin-St Jeor Equation

We use the Mifflin-St Jeor equation, published in 1990 and widely considered the most accurate BMR formula for most people. It's more accurate than the older Harris-Benedict equation and doesn't require body fat percentage like the Katch-McArdle formula.

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

The equation accounts for the metabolic differences between males and females, with men typically having 5-10% higher BMR due to greater muscle mass on average.

Understanding Macronutrients

Protein (4 cal/gram) is essential for muscle maintenance and growth, immune function, and satiety. Most adults need 0.8-1g per pound of body weight when active, with higher amounts beneficial for muscle building or weight loss to preserve lean mass.

Carbohydrates (4 cal/gram) are your body's preferred energy source, especially for high-intensity exercise. Needs vary dramatically by activity level—endurance athletes may need 60%+ of calories from carbs, while sedentary individuals can function well on much less.

Fat (9 cal/gram) is essential for hormone production, nutrient absorption, and brain function. Most authorities recommend at least 20-25% of calories from fat, with emphasis on unsaturated sources. Our calculator provides multiple macro ratio presets to match different dietary approaches.

Activity Level Selection Guide

Sedentary (1.2×): Desk job with little to no exercise. Walking only for basic needs. Most office workers without a structured exercise routine fall here.

Lightly Active (1.375×): Light exercise 1-3 days/week, or a job requiring some walking. Walking 10,000+ steps daily or light gardening/housework.

Moderately Active (1.55×): Moderate exercise 3-5 days/week. Most recreational gym-goers fit here—30-60 minute workouts several times weekly.

Active (1.725×): Hard exercise 6-7 days/week. Athletes in training, manual laborers, or those with very active hobbies. Calculate margins with our Margin Calculator.

Very Active (1.9×): Very hard exercise plus a physical job. Professional athletes, military training, or construction workers who also exercise intensively.

Frequently Asked Questions

How accurate is this calculator?

BMR equations are population averages and can vary ±10% for individuals. Use the calculator as a starting point, then adjust based on real-world results. If you're not losing/gaining as expected after 2-3 weeks, adjust calories by 100-200 in the appropriate direction.

What if I exercise some days and not others?

Choose the average activity level over a typical week. Alternatively, eat at a "rest day" level and add calories back on training days. Many people overestimate their activity level—when in doubt, choose the lower option. Check tips with our Tip Calculator.

Should I eat back exercise calories?

This is already factored into your activity multiplier. If you selected "Moderately Active" because you exercise 4x/week, those exercise calories are already included in your TDEE. Only add extra food for exercise beyond your typical routine.

How fast should I lose weight?

0.5-1% of body weight per week is generally considered safe and sustainable, maximizing fat loss while preserving muscle. For a 200 lb person, that's 1-2 lbs/week. Faster rates increase muscle loss risk and are harder to maintain.