Find your daily calorie needs using the Mifflin-St Jeor equation.
Understanding how many calories your body actually needs each day is the foundation of any informed weight management or nutrition strategy, whether the goal is weight loss, weight gain, or simply maintaining current weight. The CalcEqual Calorie Calculator uses the Mifflin-St Jeor equation — widely regarded by dietitians as the most accurate publicly available formula — to estimate your Basal Metabolic Rate (BMR), then scales that figure by your activity level to produce your Total Daily Energy Expenditure (TDEE), the number of calories you burn in a typical day including all movement and exercise.
This tool is most commonly used as a starting point for setting a calorie target: subtracting roughly 500 calories from maintenance for a sustainable ~1 pound/week weight loss pace, or adding calories above maintenance to support muscle gain or healthy weight gain. Registered dietitians and personal trainers frequently use formulas like this as a baseline before adjusting based on an individual's actual observed progress over several weeks.
It's worth recognizing that any calorie estimate — no matter how precise the formula — is still an approximation of a genuinely complex biological process. Real-world calorie needs vary based on factors like genetics, muscle mass, sleep quality, and even environmental temperature, meaning this calculator is best used as a sensible starting point to be refined through tracking your own actual results over time.
Many fitness tracking apps and wearable devices provide their own calorie burn estimates, which can sometimes differ noticeably from this calculator's TDEE figure since they often incorporate real-time heart rate data and proprietary algorithms — treating both as reasonable estimates within a normal range of variation, rather than expecting either to be perfectly precise, is the most practical approach.
The Mifflin-St Jeor equation was published in 1990 by Dr. Mark Mifflin and colleagues, developed specifically to improve upon the older Harris-Benedict equation (originally from 1919, revised in 1984), which had been shown in subsequent research to systematically overestimate BMR for the modern population. Multiple validation studies since have found Mifflin-St Jeor to be the most accurate predictive equation for the general population among commonly used formulas.
The Academy of Nutrition and Dietetics, the largest organization of food and nutrition professionals in the United States, recommends the Mifflin-St Jeor equation as the preferred method for estimating resting energy expenditure in healthy adults, a standard widely adopted across clinical and fitness nutrition practice.
Protein intake recommendations often scale alongside calorie targets, particularly during a calorie deficit, since adequate protein helps preserve lean muscle mass while losing fat — many nutrition guidelines suggest 0.7-1 gram of protein per pound of body weight for people actively trying to lose fat while maintaining strength.
Approximate activity factor multipliers used to convert BMR to TDEE:
| Activity Level | Multiplier | Description |
|---|---|---|
| Sedentary | 1.2 | Little to no exercise |
| Lightly Active | 1.375 | Light exercise 1-3 days/week |
| Moderately Active | 1.55 | Moderate exercise 3-5 days/week |
| Very Active | 1.725 | Hard exercise 6-7 days/week |
| Extra Active | 1.9 | Very hard exercise, physical job |