1. What is BMR?

Basal Metabolic Rate (BMR) is the number of calories your body needs to perform basic life-sustaining functions at rest. This calculator provides the BMR value in kilojoules (kJ) per day.

2. How Does the Calculator Work?

The calculator uses the Revised Harris-Benedict Equation:

Where:

• \( weight \) — Body weight in kilograms (kg)
• \( height \) — Height in centimeters (cm)
• \( age \) — Age in years
• \( s \) — +5 for males, -161 for females
• \( 4.184 \) — Conversion factor from kcal to kJ

Explanation: The equation calculates BMR in kilocalories first, then converts it to kilojoules using the conversion factor 4.184 kJ/kcal.

3. Importance of BMR Calculation

Details: Knowing your BMR helps in creating effective weight management plans, determining daily calorie needs, and understanding your body's energy requirements at rest.

4. Using the Calculator

Tips: Enter your weight in kg, height in cm, age in years, and select your gender. All values must be valid positive numbers.

5. Frequently Asked Questions (FAQ)

Q1: What's the difference between BMR and RMR?
A: BMR measures energy expenditure in a completely rested state, while RMR (Resting Metabolic Rate) is measured under less strict conditions and is typically slightly higher.

Q2: Why calculate BMR in kJ instead of kcal?
A: Kilojoules are the SI unit for energy and are commonly used in many countries outside the US. This calculator provides both options for international users.

Q3: How accurate is this BMR calculation?
A: While the Harris-Benedict equation provides a good estimate, individual variations in metabolism mean actual BMR may differ by ±10-15%.

Q4: When is the best time to measure BMR?
A: For most accurate results, measure after waking up, before eating or drinking, and after 8 hours of restful sleep.

Q5: Does muscle mass affect BMR?
A: Yes, muscle tissue burns more calories at rest than fat tissue. Individuals with higher muscle mass typically have higher BMR.