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)
Super active (very hard exercise & physical job)
Basal Metabolic Rate (BMR)
1,800 Calories/day
Energy burned at complete rest
Total Daily Energy Expenditure (TDEE)
2,200 Calories/day
Calories needed to maintain current weight
Calorie Needs for Goals
Goal
Daily Calories
Mild Weight Loss (-0.5 lb/week)
Weight Loss (-1 lb/week)
Extreme Weight Loss (-2 lb/week)
Mild Weight Gain (+0.5 lb/week)
Understanding Your Metabolic Rate
When you ask "what is my metabolic rate," you are essentially asking how much energy your body processes on a daily basis. This calculator provides two crucial numbers: your Basal Metabolic Rate (BMR) and your Total Daily Energy Expenditure (TDEE).
What is Basal Metabolic Rate (BMR)?
Your BMR represents the number of calories your body burns while at complete rest. Even if you stayed in bed all day, your body needs energy to breathe, circulate blood, control body temperature, and grow cells. This accounts for about 60-75% of the total calories you burn daily.
What is Total Daily Energy Expenditure (TDEE)?
While BMR is your baseline, TDEE adds the calories you burn through physical activity and the digestion of food. This is the more practical number to use when planning a diet. If you eat exactly your TDEE in calories, your weight will likely stay the same. To lose weight, you typically need to consume fewer calories than your TDEE.
Factors Influencing Metabolism
Body Size: Larger bodies generally burn more calories because they have more mass to maintain.
Muscle Mass: Muscle tissue burns more calories at rest than fat tissue. This is why strength training can increase your metabolic rate.
Age: Metabolism naturally slows down as we age, largely due to a loss of muscle mass and hormonal changes.
Gender: Men typically have less body fat and more muscle than women of the same age and weight, resulting in a higher metabolic rate.
How to Use This Data
Use the TDEE result above as a baseline. To lose about 1 pound of fat per week, a common recommendation is to create a deficit of approximately 500 calories per day (3,500 calories per week). However, it is generally advised not to drop below your BMR calories for extended periods without medical supervision, as this can slow down your metabolism further.
function toggleUnits() {
var radios = document.getElementsByName('unitSystem');
var selected = 'imperial';
for (var i = 0; i < radios.length; i++) {
if (radios[i].checked) {
selected = radios[i].value;
break;
}
}
var imperialDiv = document.getElementById('imperialInputs');
var metricDiv = document.getElementById('metricInputs');
if (selected === 'imperial') {
imperialDiv.style.display = 'block';
metricDiv.style.display = 'none';
} else {
imperialDiv.style.display = 'none';
metricDiv.style.display = 'block';
}
}
function calculateMetabolicRate() {
// 1. Get Inputs
var age = parseFloat(document.getElementById('age').value);
var genderRadios = document.getElementsByName('gender');
var gender = 'male';
for (var i = 0; i < genderRadios.length; i++) {
if (genderRadios[i].checked) {
gender = genderRadios[i].value;
break;
}
}
var activityMultiplier = parseFloat(document.getElementById('activity').value);
// Unit System Handling
var unitRadios = document.getElementsByName('unitSystem');
var unitSystem = 'imperial';
for (var j = 0; j < unitRadios.length; j++) {
if (unitRadios[j].checked) {
unitSystem = unitRadios[j].value;
break;
}
}
var weightKg = 0;
var heightCm = 0;
// 2. Validate and Convert
if (unitSystem === 'imperial') {
var feet = parseFloat(document.getElementById('feet').value);
var inches = parseFloat(document.getElementById('inches').value);
var weightLbs = parseFloat(document.getElementById('weightLbs').value);
if (isNaN(feet)) feet = 0;
if (isNaN(inches)) inches = 0;
if (isNaN(age) || isNaN(weightLbs) || (feet === 0 && inches === 0)) {
alert("Please enter valid age, height, and weight values.");
return;
}
// Conversion
weightKg = weightLbs / 2.20462;
heightCm = ((feet * 12) + inches) * 2.54;
} else {
var inputHeightCm = parseFloat(document.getElementById('heightCm').value);
var inputWeightKg = parseFloat(document.getElementById('weightKg').value);
if (isNaN(age) || isNaN(inputHeightCm) || isNaN(inputWeightKg)) {
alert("Please enter valid age, height, and weight values.");
return;
}
weightKg = inputWeightKg;
heightCm = inputHeightCm;
}
// 3. Mifflin-St Jeor Equation
// 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 = (10 * weightKg) + (6.25 * heightCm) – (5 * age);
if (gender === 'male') {
bmr += 5;
} else {
bmr -= 161;
}
// 4. Calculate TDEE
var tdee = bmr * activityMultiplier;
// 5. Update UI
document.getElementById('bmrValue').innerHTML = Math.round(bmr).toLocaleString();
document.getElementById('tdeeValue').innerHTML = Math.round(tdee).toLocaleString();
// Weight Goals
document.getElementById('lossMild').innerHTML = Math.round(tdee * 0.90) + " cal"; // approx 250 deficit usually, or % based. Let's do standard 250/500/1000
document.getElementById('lossNormal').innerHTML = Math.round(tdee – 500) + " cal";
document.getElementById('lossExtreme').innerHTML = Math.round(tdee – 1000) + " cal";
// Safety check for extreme loss not going below BMR too much or 1200
var extremeVal = Math.round(tdee – 1000);
if (extremeVal < 1200) {
document.getElementById('lossExtreme').innerHTML = extremeVal + " cal (Not Recommended)";
}
document.getElementById('gainMild').innerHTML = Math.round(tdee + 250) + " cal";
document.getElementById('bmr-results').style.display = 'block';
}