Baseline Metabolic Rate Calculator

What is Baseline Metabolic Rate (BMR)?

Your Baseline Metabolic Rate (BMR), also known as your resting metabolic rate, is the minimum number of calories your body needs to perform its basic life-sustaining functions while at rest. These functions include breathing, circulating blood, regulating body temperature, and cell production. Essentially, it's the energy your body burns just to keep you alive and functioning, even if you were to spend the entire day lying down and doing nothing.

Factors Affecting BMR:

• Age: BMR generally decreases with age as muscle mass tends to decline.
• Sex: Men typically have a higher BMR than women due to a higher proportion of muscle mass.
• Body Composition: Muscle tissue burns more calories at rest than fat tissue. Therefore, individuals with more muscle mass have a higher BMR.
• Body Size: Larger individuals generally have a higher BMR because they have more tissue to maintain.
• Hormones: Thyroid hormones, for instance, play a significant role in regulating metabolism.
• Genetics: Your genetic makeup can influence how efficiently your body uses energy.
• Environmental Temperature: Your body may burn more calories to maintain its temperature in very cold or very hot environments.

Why is BMR Important?

Understanding your BMR is a foundational step in managing your weight and overall health. It helps you estimate the total number of calories you burn daily (Total Daily Energy Expenditure or TDEE) by factoring in your activity level. Knowing your BMR allows for more informed decisions about your dietary intake and exercise routine, whether your goal is to lose weight, gain muscle, or maintain your current physique.

How is BMR Calculated?

There are several formulas to estimate BMR, with the most common ones being the Harris-Benedict Equation and the Mifflin-St Jeor Equation. The Mifflin-St Jeor Equation is generally considered more accurate for most people.

Calculate Your Baseline Metabolic Rate (BMR)

Please enter your details below. We will use the Mifflin-St Jeor Equation, which is widely regarded as the most accurate for estimating BMR.

function calculateBMR() { var weightKg = document.getElementById("weightKg").value; var heightCm = document.getElementById("heightCm").value; var ageYears = document.getElementById("ageYears").value; var gender = document.getElementById("gender").value; var resultDiv = document.getElementById("result"); resultDiv.innerHTML = ""; // Clear previous results // Validate inputs if (weightKg === "" || heightCm === "" || ageYears === "") { resultDiv.innerHTML = "Please fill in all fields."; return; } var weight = parseFloat(weightKg); var height = parseFloat(heightCm); var age = parseFloat(ageYears); if (isNaN(weight) || isNaN(height) || isNaN(age) || weight <= 0 || height <= 0 || age <= 0) { resultDiv.innerHTML = "Please enter valid positive numbers for weight, height, and age."; return; } var bmr = 0; // Mifflin-St Jeor Equation if (gender === "male") { bmr = (10 * weight) + (6.25 * height) – (5 * age) + 5; } else { // female bmr = (10 * weight) + (6.25 * height) – (5 * age) – 161; } // Display result resultDiv.innerHTML = "Your estimated Baseline Metabolic Rate (BMR) is: " + bmr.toFixed(2) + " calories per day"; }