Your Estimated BMR
This is the minimum number of calories your body burns at rest to maintain essential functions like breathing, circulation, and cell production. Your total daily energy expenditure will be higher, depending on your activity level.
.calculator-wrapper {
font-family: sans-serif;
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padding: 20px;
border-radius: 8px;
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margin: 20px auto;
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gap: 20px;
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min-width: 250px;
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padding: 15px;
border-radius: 5px;
border: 1px solid #eee;
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margin-bottom: 15px;
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.input-group label {
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.input-group input[type="number"],
.input-group select {
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padding: 8px;
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width: 100%;
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.calculator-inputs button:hover {
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#result h3 {
margin-top: 0;
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#bmrValue {
font-size: 24px;
font-weight: bold;
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function calculateBMR() {
var gender = document.getElementById("gender").value;
var weight = parseFloat(document.getElementById("weight").value);
var height = parseFloat(document.getElementById("height").value);
var age = parseFloat(document.getElementById("age").value);
var bmr = 0;
if (isNaN(weight) || isNaN(height) || isNaN(age) || weight <= 0 || height <= 0 || age <= 0) {
document.getElementById("bmrValue").innerHTML = "Please enter valid positive numbers for weight, height, and age.";
return;
}
if (gender === "male") {
bmr = (10 * weight) + (6.25 * height) – (5 * age) + 5;
} else { // female
bmr = (10 * weight) + (6.25 * height) – (5 * age) – 161;
}
document.getElementById("bmrValue").innerHTML = bmr.toFixed(2) + " calories";
}
**Understanding Basal Metabolic Rate (BMR)**
Your Basal Metabolic Rate (BMR) represents the absolute minimum number of calories your body requires to function while at rest. Think of it as the energy your body expends to keep vital organs like your heart, lungs, brain, and kidneys working, as well as to maintain body temperature, circulation, and cellular activities. This is the energy your body would burn if you were to lie perfectly still in a temperate environment all day without any digestion.
The Mifflin-St Jeor equation is a popular and well-researched formula used to estimate BMR. It takes into account your gender, weight, height, and age. These factors influence your metabolic rate because:
* **Gender:** Men typically have more lean muscle mass than women, which burns more calories at rest, leading to a higher BMR.
* **Weight:** More body mass, particularly muscle, requires more energy to sustain.
* **Height:** Taller individuals generally have a larger body surface area and more cells, contributing to a higher BMR.
* **Age:** BMR tends to decrease with age, largely due to a natural decline in muscle mass and metabolic efficiency.
**How BMR Differs from Total Daily Energy Expenditure (TDEE)**
It's crucial to understand that BMR is just one component of your total daily calorie needs. Your TDEE (Total Daily Energy Expenditure) accounts for your BMR plus the calories burned through physical activity (exercise and non-exercise activity thermogenesis – NEAT), and the thermic effect of food (TEF – the calories burned digesting and absorbing food).
To determine your total calorie needs for weight management or muscle gain, you would multiply your BMR by an activity factor that reflects your lifestyle. For example:
* **Sedentary:** Little to no exercise (BMR x 1.2)
* **Lightly active:** Exercise 1-3 days/week (BMR x 1.375)
* **Moderately active:** Exercise 3-5 days/week (BMR x 1.55)
* **Very active:** Exercise 6-7 days/week (BMR x 1.725)
* **Extra active:** Very intense exercise daily, or physical job (BMR x 1.9)
**Example Calculation:**
Let's calculate the BMR for a 35-year-old male, weighing 80 kg, and standing 180 cm tall.
* **Gender:** Male
* **Weight:** 80 kg
* **Height:** 180 cm
* **Age:** 35 years
Using the Mifflin-St Jeor equation for males:
BMR = (10 × Weight in kg) + (6.25 × Height in cm) – (5 × Age in years) + 5
BMR = (10 × 80) + (6.25 × 180) – (5 × 35) + 5
BMR = 800 + 1125 – 175 + 5
BMR = 1755 calories
So, this individual's estimated Basal Metabolic Rate is 1755 calories per day. If this individual leads a moderately active lifestyle (BMR x 1.55), their estimated TDEE would be approximately 2720 calories per day (1755 * 1.55).