This calculator helps you determine your Body Mass Index (BMI) and Basal Metabolic Rate (BMR) based on your age, height, weight, and sex. These metrics can provide insights into your general health and metabolic needs.
function calculateHealthMetrics() {
var ageYears = parseFloat(document.getElementById('ageYears').value);
var heightCm = parseFloat(document.getElementById('heightCm').value);
var weightKg = parseFloat(document.getElementById('weightKg').value);
var sexMale = document.getElementById('sexMale').checked;
var bmiResultDiv = document.getElementById('bmiResult');
var bmrResultDiv = document.getElementById('bmrResult');
// Input validation
if (isNaN(ageYears) || ageYears <= 0) {
bmiResultDiv.innerHTML = 'Please enter a valid positive age.';
bmrResultDiv.innerHTML = '';
return;
}
if (isNaN(heightCm) || heightCm <= 0) {
bmiResultDiv.innerHTML = 'Please enter a valid positive height.';
bmrResultDiv.innerHTML = '';
return;
}
if (isNaN(weightKg) || weightKg <= 0) {
bmiResultDiv.innerHTML = 'Please enter a valid positive weight.';
bmrResultDiv.innerHTML = '';
return;
}
// Calculate BMI
var heightMeters = heightCm / 100;
var bmi = weightKg / (heightMeters * heightMeters);
var bmiCategory = '';
if (bmi = 18.5 && bmi = 25 && bmi < 29.9) {
bmiCategory = 'Overweight';
} else {
bmiCategory = 'Obese';
}
bmiResultDiv.innerHTML = '
' + bmi.toFixed(2) + ' (' + bmiCategory + ')';
// Calculate BMR (Basal Metabolic Rate) using Mifflin-St Jeor Equation
var bmr;
if (sexMale) {
bmr = (10 * weightKg) + (6.25 * heightCm) – (5 * ageYears) + 5;
} else { // Female
bmr = (10 * weightKg) + (6.25 * heightCm) – (5 * ageYears) – 161;
}
bmrResultDiv.innerHTML = '
' + bmr.toFixed(0) + ' calories/day';
}
.age-height-weight-calculator-container {
font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
background-color: #f9f9f9;
padding: 25px;
border-radius: 10px;
box-shadow: 0 4px 12px rgba(0, 0, 0, 0.1);
max-width: 600px;
margin: 30px auto;
border: 1px solid #e0e0e0;
}
.age-height-weight-calculator-container h2 {
color: #333;
text-align: center;
margin-bottom: 20px;
font-size: 1.8em;
}
.age-height-weight-calculator-container p {
color: #555;
text-align: center;
margin-bottom: 25px;
line-height: 1.6;
}
.calculator-form .form-group {
margin-bottom: 18px;
display: flex;
flex-direction: column;
}
.calculator-form label {
font-weight: bold;
margin-bottom: 8px;
color: #444;
font-size: 1em;
}
.calculator-form input[type="number"] {
padding: 12px;
border: 1px solid #ccc;
border-radius: 6px;
font-size: 1em;
width: 100%;
box-sizing: border-box;
transition: border-color 0.3s ease;
}
.calculator-form input[type="number"]:focus {
border-color: #007bff;
outline: none;
box-shadow: 0 0 0 3px rgba(0, 123, 255, 0.25);
}
.calculator-form .radio-group {
display: flex;
gap: 20px;
margin-top: 5px;
}
.calculator-form .radio-group input[type="radio"] {
margin-right: 5px;
transform: scale(1.2);
}
.calculator-form .radio-group label {
font-weight: normal;
color: #555;
margin-bottom: 0;
display: flex;
align-items: center;
cursor: pointer;
}
.calculator-form button {
background-color: #007bff;
color: white;
padding: 14px 25px;
border: none;
border-radius: 6px;
font-size: 1.1em;
cursor: pointer;
transition: background-color 0.3s ease, transform 0.2s ease;
width: 100%;
margin-top: 20px;
box-shadow: 0 2px 8px rgba(0, 123, 255, 0.2);
}
.calculator-form button:hover {
background-color: #0056b3;
transform: translateY(-2px);
}
.calculator-form button:active {
transform: translateY(0);
box-shadow: 0 1px 4px rgba(0, 123, 255, 0.3);
}
.calculator-results {
margin-top: 30px;
padding-top: 25px;
border-top: 1px solid #eee;
text-align: center;
}
.calculator-results h3 {
color: #333;
margin-bottom: 15px;
font-size: 1.5em;
}
.calculator-results .result-item {
background-color: #e9f7ff;
border: 1px solid #cce5ff;
padding: 15px;
margin-bottom: 10px;
border-radius: 8px;
color: #004085;
font-size: 1.1em;
font-weight: 500;
}
.calculator-results .result-item strong {
color: #002752;
}
Understanding Your BMI and BMR
Your Body Mass Index (BMI) and Basal Metabolic Rate (BMR) are two fundamental metrics used to assess your body composition and energy needs. While they are not definitive health indicators on their own, they provide valuable starting points for understanding your body.
What is Body Mass Index (BMI)?
BMI is a simple calculation using a person's height and weight. The formula is weight (kg) / [height (m)]2. It's a screening tool that categorizes individuals into weight ranges: underweight, normal weight, overweight, and obese. A higher BMI can indicate a higher risk for certain health conditions, but it doesn't directly measure body fat or distinguish between muscle and fat mass. For example, a very muscular athlete might have a high BMI but a low body fat percentage.
BMI Categories for Adults:
- Underweight: Less than 18.5
- Normal weight: 18.5 – 24.9
- Overweight: 25 – 29.9
- Obese: 30 or greater
It's important to consult a healthcare professional for a comprehensive health assessment, as BMI should be considered alongside other factors like age, sex, body composition, and ethnic background.
What is Basal Metabolic Rate (BMR)?
Your Basal Metabolic Rate (BMR) is the number of calories your body needs to perform basic, life-sustaining functions while at rest. These essential functions include breathing, circulation, cell production, nutrient processing, and maintaining body temperature. In essence, it's the energy your body burns just to keep you alive, even if you were to do nothing but sleep all day.
The calculator uses the Mifflin-St Jeor equation, which is widely considered one of the most accurate formulas for estimating BMR:
- 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
Your BMR accounts for about 60-75% of your total daily energy expenditure. Factors like age, sex, weight, height, and genetics all influence your BMR. For instance, BMR generally decreases with age and is typically higher in men due to a greater muscle mass.
How to Use These Metrics
Knowing your BMI can help you understand if your weight is in a healthy range relative to your height. Your BMR is crucial for understanding your daily caloric needs. If you're looking to maintain your weight, you'd aim to consume roughly your BMR plus the calories burned through physical activity. If you want to lose weight, you'd aim for a caloric intake slightly below this total, and for weight gain, slightly above.
Remember, these calculators provide estimates. For personalized health and dietary advice, always consult with a doctor or a registered dietitian.
Example Calculation:
Let's consider a 30-year-old male, 175 cm tall, weighing 70 kg:
- Height in meters: 175 cm / 100 = 1.75 m
- BMI: 70 kg / (1.75 m * 1.75 m) = 70 / 3.0625 = 22.86 (Normal weight)
- BMR (Male): (10 * 70) + (6.25 * 175) – (5 * 30) + 5
- = 700 + 1093.75 – 150 + 5
- = 1648.75 calories/day (approximately 1649 calories/day)
This individual has a normal BMI and requires about 1649 calories per day just for basic bodily functions. Any additional physical activity would increase their total daily caloric needs.