Calorie Calculator
Understanding Results
Related Calculators
Understanding Calories and Weight Management
What is a Calorie?
A calorie is a unit of energy. In nutrition, we actually use kilocalories (kcal), often just called "calories." Your body needs energy to function—even at rest, you burn calories to breathe, circulate blood, and maintain body temperature.
BMR vs TDEE
Basal Metabolic Rate (BMR)
The number of calories your body burns at complete rest—just to keep you alive. This accounts for 60-75% of daily calorie burn.
Total Daily Energy Expenditure (TDEE)
Your BMR plus calories burned through activity, exercise, and digesting food. This is your maintenance level.
The Mifflin-St Jeor Equation
This calculator uses the Mifflin-St Jeor equation, considered the most accurate BMR formula:
Men: BMR = 10 × weight(kg) + 6.25 × height(cm) - 5 × age + 5
Women: BMR = 10 × weight(kg) + 6.25 × height(cm) - 5 × age - 161
Activity Level Multipliers
| Activity Level | Description | Multiplier |
|---|---|---|
| Sedentary | Little or no exercise, desk job | BMR × 1.2 |
| Light | Light exercise 1-3 days/week | BMR × 1.375 |
| Moderate | Moderate exercise 3-5 days/week | BMR × 1.55 |
| Active | Hard exercise 6-7 days/week | BMR × 1.725 |
| Very Active | Very hard exercise, physical job | BMR × 1.9 |
Weight Loss vs Weight Gain
The 500-Calorie Rule:
- • To lose ~1 lb/week: Eat 500 calories below TDEE
- • To gain ~1 lb/week: Eat 500 calories above TDEE
- • 1 pound of body fat ≈ 3,500 calories
Macronutrient Breakdown
Calories come from three macronutrients:
- Protein: 4 calories per gram - Essential for muscle, repair, and satiety
- Carbohydrates: 4 calories per gram - Primary energy source
- Fat: 9 calories per gram - Essential for hormones and nutrient absorption
Important Note
These calculations provide estimates. Individual metabolism varies based on genetics, muscle mass, hormones, and other factors. Monitor your progress and adjust as needed. Consult a healthcare provider before starting any significant diet change.
Frequently Asked Questions
How many calories should I eat to lose weight?
To lose weight safely, create a calorie deficit of 500-750 calories below your TDEE (Total Daily Energy Expenditure). This typically results in 1-1.5 pounds of weight loss per week. Never go below 1,200 calories (women) or 1,500 calories (men) without medical supervision, as this can lead to nutrient deficiencies and metabolic slowdown.
What is the difference between BMR and TDEE?
BMR (Basal Metabolic Rate) is the number of calories your body burns at complete rest just to maintain vital functions like breathing and circulation. TDEE (Total Daily Energy Expenditure) is your BMR plus all calories burned through daily activities, exercise, and digesting food. TDEE is the number you should base your diet on.
Why is the Mifflin-St Jeor equation used for calorie calculations?
The Mifflin-St Jeor equation is considered the most accurate formula for estimating BMR, typically within 10% of actual metabolic rate for most people. Developed in 1990, it outperforms older formulas like Harris-Benedict because it better reflects modern body compositions and lifestyles.
How do I know if my calorie estimate is accurate?
Calorie calculators provide estimates that work for most people, but individual metabolism varies. Track your weight for 2-3 weeks while eating at your calculated calories. If you're not seeing expected results, adjust by 100-200 calories. Factors like muscle mass, hormones, sleep quality, and stress can affect actual calorie needs.