Basal Caloric Rate Calculator

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Basal Metabolic Rate (BMR) Calculator

Male Female
Your Basal Metabolic Rate (BMR) will be displayed here.
.calculator-container { font-family: sans-serif; border: 1px solid #ccc; padding: 20px; border-radius: 8px; max-width: 500px; margin: 20px auto; background-color: #f9f9f9; } .calculator-title { text-align: center; margin-bottom: 20px; color: #333; } .calculator-inputs { display: grid; grid-template-columns: 1fr; gap: 15px; } .input-group { display: flex; flex-direction: column; margin-bottom: 15px; } .input-group label { margin-bottom: 5px; font-weight: bold; color: #555; } .input-group input[type="number"], .input-group select { padding: 10px; border: 1px solid #ccc; border-radius: 4px; font-size: 1rem; } button { background-color: #4CAF50; color: white; padding: 12px 20px; border: none; border-radius: 4px; cursor: pointer; font-size: 1rem; transition: background-color 0.3s ease; } button:hover { background-color: #45a049; } .calculator-result { margin-top: 25px; padding: 15px; border: 1px solid #ddd; border-radius: 4px; background-color: #fff; text-align: center; font-size: 1.1rem; color: #333; } function calculateBMR() { var gender = document.getElementById("gender").value; var weightKg = parseFloat(document.getElementById("weightKg").value); var heightCm = parseFloat(document.getElementById("heightCm").value); var age = parseFloat(document.getElementById("age").value); var bmr = 0; if (isNaN(weightKg) || isNaN(heightCm) || isNaN(age) || weightKg <= 0 || heightCm <= 0 || age <= 0) { document.getElementById("result").innerHTML = "Please enter valid positive numbers for weight, height, and age."; return; } if (gender === "male") { // Mifflin-St Jeor Equation for Men bmr = (10 * weightKg) + (6.25 * heightCm) – (5 * age) + 5; } else { // Mifflin-St Jeor Equation for Women bmr = (10 * weightKg) + (6.25 * heightCm) – (5 * age) – 161; } document.getElementById("result").innerHTML = "Your Basal Metabolic Rate (BMR) is: " + bmr.toFixed(2) + " calories/day"; }

Understanding Your Basal Metabolic Rate (BMR)

Your Basal Metabolic Rate (BMR) represents the minimum number of calories your body needs to perform essential life-sustaining functions at rest. These vital functions include breathing, circulating blood, maintaining body temperature, cell production, and brain and nerve function. Think of it as the energy your body expends just to keep you alive and functioning, even if you were to sleep all day.

Several factors influence your BMR, including:

  • Body Composition: Muscle tissue burns more calories at rest than fat tissue. Individuals with a higher muscle mass generally have a higher BMR.
  • Age: BMR typically decreases as people age, partly due to a natural decline in muscle mass.
  • Gender: Men generally have a higher BMR than women, primarily because they tend to have more muscle mass and a larger body size.
  • Genetics: Your inherited traits can play a role in your metabolic rate.
  • Body Size and Shape: Larger individuals usually have higher BMRs.
  • Hormonal Levels: Thyroid hormones, for instance, significantly impact metabolism.

Why is BMR Important?

Understanding your BMR is a crucial first step in managing your weight and overall health. Your total daily energy expenditure (TDEE) is your BMR plus the calories you burn through physical activity and the thermic effect of food (the energy used to digest and absorb food). By knowing your BMR, you can more accurately estimate how many calories you need to consume to maintain, lose, or gain weight. For example, if your goal is weight loss, you'll generally need to consume fewer calories than your TDEE.

The Mifflin-St Jeor Equation

The calculator above uses the Mifflin-St Jeor equation, which is widely considered one of the most accurate formulas for estimating BMR. The formulas are:

  • For Men: BMR = (10 × weight in kg) + (6.25 × height in cm) – (5 × age in years) + 5
  • For Women: BMR = (10 × weight in kg) + (6.25 × height in cm) – (5 × age in years) – 161

Example Calculation:

Let's consider a 35-year-old male who weighs 80 kg and is 180 cm tall.

Using the Mifflin-St Jeor equation for men:

BMR = (10 * 80) + (6.25 * 180) – (5 * 35) + 5
BMR = 800 + 1125 – 175 + 5
BMR = 1755 calories/day

This means this individual needs approximately 1755 calories per day to sustain basic bodily functions while at rest.

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