What Are Calories, and How Are They Calculated?
A calorie is a unit of energy your body gets from food and drink, and spends on everything: breathing, your heartbeat, walking, and exercise. Knowing your daily need is the starting point for any weight goal — whether losing, maintaining, or gaining weight healthily.
The Mifflin-St Jeor Equation
This calculator uses the Mifflin-St Jeor equation, one of the most accurate and widely trusted formulas in medical and nutrition practice for calculating Basal Metabolic Rate (BMR):
Men: BMR = (10 × weight kg) + (6.25 × height cm) − (5 × age) + 5
Women: BMR = (10 × weight kg) + (6.25 × height cm) − (5 × age) − 161
BMR is then multiplied by an activity factor to get Total Daily Energy Expenditure (TDEE) — the real number to use when planning your diet.
Activity Level Factors
| Activity Level | Description | Factor |
|---|---|---|
| Sedentary | Little movement or desk job with no exercise | 1.2 |
| Light | Light exercise 1–3 times/week | 1.375 |
| Moderate | Moderate exercise 3–5 times/week | 1.55 |
| High | Intense exercise 6–7 times/week | 1.725 |
| Very High | Daily strenuous exercise or hard physical labor | 1.9 |
How to Use Your Result
- If your goal is maintaining your weight, eat roughly your TDEE number daily.
- To lose weight safely, subtract 300–500 calories from your TDEE — about half a kilogram per week.
- To gain weight or build muscle, add 300–500 calories and pay attention to protein sources.
- Recalculate every 4–6 weeks, since your weight and activity change and the numbers should keep up.