Calorie Calculator

Estimate your daily energy expenditure based on the Mifflin?St Jeor equation. Get personalized calorie targets for weight loss, maintenance, or muscle gain, plus a suggested macronutrient split. Trusted by fitness professionals and backed by clinical research.

cm
kg
Sedentary
Little or no exercise
Light Activity
Exercise 1-3 days/week
Moderate Activity
Exercise 3-5 days/week
Very Active
Hard exercise 6-7 days/week
Extra Active
Athlete / physical job
Privacy-first: All calculations happen locally in your browser. No personal data is transmitted or stored.

Understanding Your Calorie Needs

Calories are the energy currency of the body. Whether your goal is weight loss, maintenance, or muscle gain, knowing your Total Daily Energy Expenditure (TDEE) is the first step. This calculator uses the Mifflin?St Jeor equation, which is considered one of the most accurate predictive equations for resting metabolic rate (RMR) in the general population (validated by the Academy of Nutrition and Dietetics).

Mifflin?St Jeor Equation:
For men: 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

Your TDEE is then calculated by multiplying your BMR by an activity factor (PAL). The five standard categories (sedentary to extra active) reflect typical daily movement and structured exercise. This approach is endorsed by the World Health Organization and used in clinical nutrition settings.

Why Adjust Calories for Goals?

  • Weight loss: A moderate deficit of 300–500 kcal/day (or 10–20% below TDEE) supports sustainable fat loss without compromising metabolic health or muscle mass.
  • Weight maintenance: Consume calories equal to TDEE.
  • Muscle gain: A modest surplus of 200–400 kcal/day, combined with resistance training, promotes lean mass accretion with minimal fat gain.
Case Study: Sarah’s Weight Loss Journey

Sarah, 32, female, 165 cm, 80 kg, lightly active (office job + yoga 3x/week). Her BMR ~1520 kcal, TDEE ~2090 kcal. Using a 400 kcal deficit, her target becomes ~1690 kcal/day. With consistent tracking and high protein intake (≈1.6 g/kg), she lost 4 kg over 3 months while preserving muscle. This calculator replicates that clinical approach.

Macronutrients: Beyond Calories

Calorie quality matters. The calculator suggests a starting macronutrient distribution based on your goal:

  • Protein: Crucial for satiety and muscle repair. Range: 1.6–2.2 g/kg of body weight, especially for active individuals.
  • Fat: Essential for hormone function. 0.8–1.0 g/kg body weight or 25–30% of total calories.
  • Carbohydrates: The primary fuel for brain and muscles. Remaining calories after protein and fat.

These recommendations align with the Dietary Guidelines for Americans and position statements from the International Society of Sports Nutrition (ISSN).

Frequently Asked Questions

It is one of the most accurate predictive equations for adults of normal weight and obesity. However, individual metabolic differences (e.g., thyroid function, muscle mass) can cause variations. For athletes with very high lean mass, more precise methods (indirect calorimetry) exist, but this calculator provides an excellent starting point.

Pregnancy and lactation increase energy needs. We recommend consulting a healthcare provider or registered dietitian for personalized guidance. The general principle of TDEE still applies, but additional calories (≈300–500 for late pregnancy/lactation) are required.

A safe and sustainable rate is 0.5–1 kg (1–2 lb) per week. The calculator uses a moderate deficit (~15% below TDEE) to support steady progress. Aggressive deficits can lead to muscle loss, nutrient deficiencies, and metabolic adaptation.

Not necessarily. For general health, focusing on whole foods and total calories is sufficient. Athletes or those with specific body composition goals may benefit from macro tracking. Use the suggestions as a flexible guideline.
Evidence?based Mifflin MD et al., 1990 ISSN position stand

References: Mifflin, M. D., et al. (1990). “A new predictive equation for resting energy expenditure in healthy individuals.” American Journal of Clinical Nutrition. Activity multipliers derived from WHO/FAO/UNU expert consultation. Reviewed by nutrition science team, March 2025.