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)
The total metabolic rate is calculated by adding the following components:
Basal Metabolic Rate (BMR):0 kcal/day
Thermic Effect of Food (TEF):0 kcal/day
Physical Activity Expenditure:0 kcal/day
Total Metabolic Rate (TMR):0 kcal/day
How Total Metabolic Rate is Calculated
Your Total Metabolic Rate (TMR), often referred to as Total Daily Energy Expenditure (TDEE), represents the total amount of energy (calories) your body burns in a single day. As demonstrated in the calculator above, the total metabolic rate is calculated by adding the three distinct components of energy expenditure:
Basal Metabolic Rate (BMR): This is the energy required to maintain basic physiological functions while at rest, such as breathing, circulating blood, and cell production. It typically accounts for 60-70% of total energy use.
Thermic Effect of Food (TEF): This represents the energy required to digest, absorb, and metabolize the food you eat. It generally accounts for about 10% of your total daily energy expenditure.
Physical Activity Energy Expenditure (PAEE): This includes energy burned during exercise (EAT – Exercise Activity Thermogenesis) and non-exercise movements like walking, standing, or fidgeting (NEAT – Non-Exercise Activity Thermogenesis).
The Formulas Used
This calculator utilizes the Mifflin-St Jeor equation to determine your base BMR, which is currently considered the standard for reliability in clinical settings. The formula varies slightly based on gender:
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
Once the BMR is established, activity multipliers are applied to determine the total energy output required to maintain your current weight.
function toggleUnits() {
var metricInputs = document.getElementById('metric-inputs');
var imperialInputs = document.getElementById('imperial-inputs');
var radios = document.getElementsByName('unitSystem');
var isMetric = true;
for (var i = 0; i < radios.length; i++) {
if (radios[i].checked && radios[i].value === 'imperial') {
isMetric = false;
}
}
if (isMetric) {
metricInputs.classList.remove('hidden');
imperialInputs.classList.add('hidden');
} else {
metricInputs.classList.add('hidden');
imperialInputs.classList.remove('hidden');
}
}
function calculateTMR() {
// Inputs
var gender = document.getElementById('gender').value;
var age = parseFloat(document.getElementById('age').value);
var activityMultiplier = parseFloat(document.getElementById('activity').value);
var weightKg = 0;
var heightCm = 0;
// Determine Unit System
var radios = document.getElementsByName('unitSystem');
var isMetric = true;
for (var i = 0; i < radios.length; i++) {
if (radios[i].checked && radios[i].value === 'imperial') {
isMetric = false;
}
}
// Get and Convert Weight/Height
if (isMetric) {
weightKg = parseFloat(document.getElementById('weight-kg').value);
heightCm = parseFloat(document.getElementById('height-cm').value);
} else {
var weightLbs = parseFloat(document.getElementById('weight-lbs').value);
var heightFt = parseFloat(document.getElementById('height-ft').value);
var heightIn = parseFloat(document.getElementById('height-in').value);
// Validation for Imperial
if (isNaN(heightFt)) heightFt = 0;
if (isNaN(heightIn)) heightIn = 0;
weightKg = weightLbs / 2.20462;
heightCm = ((heightFt * 12) + heightIn) * 2.54;
}
// Validate
if (isNaN(weightKg) || isNaN(heightCm) || isNaN(age) || weightKg <= 0 || heightCm <= 0) {
alert("Please enter valid weight, height, and age values.");
return;
}
// 1. Calculate BMR (Mifflin-St Jeor Equation)
var bmr = 0;
if (gender === 'male') {
bmr = (10 * weightKg) + (6.25 * heightCm) – (5 * age) + 5;
} else {
bmr = (10 * weightKg) + (6.25 * heightCm) – (5 * age) – 161;
}
// 2. Calculate Total Metabolic Rate (TDEE) based on multiplier
var totalTMR = bmr * activityMultiplier;
// 3. Deconstruct Components for "Adding" Visualization
// Standard Estimate: TEF is ~10% of Total Daily Energy Expenditure
var tef = totalTMR * 0.10;
// Physical Activity is the remainder after BMR and TEF
// Activity = Total – BMR – TEF
var activityExpenditure = totalTMR – bmr – tef;
// Rounding
bmr = Math.round(bmr);
tef = Math.round(tef);
activityExpenditure = Math.round(activityExpenditure);
totalTMR = Math.round(totalTMR);
// Display Results
document.getElementById('res-bmr').innerText = bmr.toLocaleString() + " kcal/day";
document.getElementById('res-tef').innerText = tef.toLocaleString() + " kcal/day";
document.getElementById('res-activity').innerText = activityExpenditure.toLocaleString() + " kcal/day";
document.getElementById('res-total').innerText = totalTMR.toLocaleString() + " kcal/day";
document.getElementById('tmr-result').style.display = 'block';
}