Sedentary (little or no exercise)
Lightly active (light exercise 1-3 days/week)
Moderately active (moderate exercise 3-5 days/week)
Very active (hard exercise 6-7 days/week)
Extra active (very hard exercise & physical job)
Please enter valid numeric values for age, height, and weight.
Basal Metabolic Rate (BMR):
0 kcal/day
Total Daily Energy Expenditure (TDEE):
0 kcal/day
This is the estimated amount of calories you burn per day to maintain your current weight based on the metric Mifflin-St Jeor equation.
function calculateMetabolicRate() {
// Get input values
var gender = document.getElementById('metric-gender').value;
var age = document.getElementById('metric-age').value;
var height = document.getElementById('metric-height').value;
var weight = document.getElementById('metric-weight').value;
var activityMultiplier = document.getElementById('metric-activity').value;
var errorMsg = document.getElementById('bmr-error-msg');
var resultsArea = document.getElementById('bmr-results-area');
// Parse numbers
var ageNum = parseFloat(age);
var heightNum = parseFloat(height);
var weightNum = parseFloat(weight);
var activityNum = parseFloat(activityMultiplier);
// Validation
if (isNaN(ageNum) || isNaN(heightNum) || isNaN(weightNum) || ageNum <= 0 || heightNum <= 0 || weightNum <= 0) {
errorMsg.style.display = 'block';
resultsArea.style.display = 'none';
return;
}
errorMsg.style.display = 'none';
// Mifflin-St Jeor Equation Calculation
// Men: (10 × weight in kg) + (6.25 × height in cm) – (5 × age in years) + 5
// Women: (10 × weight in kg) + (6.25 × height in cm) – (5 × age in years) – 161
var bmr = 0;
if (gender === 'male') {
bmr = (10 * weightNum) + (6.25 * heightNum) – (5 * ageNum) + 5;
} else {
bmr = (10 * weightNum) + (6.25 * heightNum) – (5 * ageNum) – 161;
}
// Calculate TDEE
var tdee = bmr * activityNum;
// Display results
document.getElementById('result-bmr').innerHTML = Math.round(bmr).toLocaleString() + ' kcal/day';
document.getElementById('result-tdee').innerHTML = Math.round(tdee).toLocaleString() + ' kcal/day';
resultsArea.style.display = 'block';
}
Understanding Your Metabolic Rate (Metric System)
Your metabolic rate is the amount of energy (calories) your body expends to perform vital functions such as breathing, circulating blood, and cell production. Understanding these numbers is the first step toward effective weight management, whether you are looking to lose fat, gain muscle, or maintain your current physique.
This calculator utilizes the metric system (kilograms and centimeters) to provide precise estimations of your Basal Metabolic Rate (BMR) and Total Daily Energy Expenditure (TDEE).
What is BMR (Basal Metabolic Rate)?
Basal Metabolic Rate represents the number of calories your body burns at complete rest. Imagine lying in bed all day without moving; this is the energy required just to keep you alive. BMR accounts for approximately 60% to 75% of your total daily calorie burn.
How It Is Calculated: The Mifflin-St Jeor Equation
Our tool uses the Mifflin-St Jeor equation, which is widely considered one of the most accurate formulas for calculating BMR in modern populations. The formula specifically relies on metric inputs:
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
Total Daily Energy Expenditure (TDEE)
While BMR tells you what you burn at rest, your TDEE adjusts this number based on your physical activity level. This is the more practical number to use when planning a diet.
Activity Level
Multiplier
Description
Sedentary
1.2
Desk job, little to no exercise
Lightly Active
1.375
Light exercise/sports 1-3 days/week
Moderately Active
1.55
Moderate exercise/sports 3-5 days/week
Very Active
1.725
Hard exercise/sports 6-7 days/week
Extra Active
1.9
Very hard exercise & physical job
How to Use These Numbers
Once you have calculated your TDEE using the metric inputs above, you can determine your caloric needs based on your specific goals:
Weight Maintenance: Consume calories equal to your TDEE.
Weight Loss: Create a calorie deficit by consuming 500 calories less than your TDEE per day (approx. 0.5 kg loss per week).
Weight Gain: Create a surplus by consuming 250-500 calories more than your TDEE per day to support muscle growth.
Why Use Metric Units?
In scientific and medical communities, the metric system is the standard for metabolic calculations. Using kilograms for weight and centimeters for height eliminates conversion errors that often occur when using imperial units (pounds and feet/inches), leading to a more accurate estimation of your daily energy needs.