How to Calculate Health

Calculating health metrics is essential for understanding your body's composition, energy needs, and overall well-being. This guide explains how to calculate key health indicators like BMI, BMR, TDEE, body fat percentage, and waist-to-hip ratio using our calculators and formulas.

BMI Calculator

The Body Mass Index (BMI) is a simple calculation that relates weight to height. It's commonly used to classify underweight, normal weight, overweight, and obesity.

BMI Formula

BMI = Weight (kg) / (Height (m) × Height (m))

Use our BMI calculator to determine your BMI category based on your weight and height. The results are categorized as follows:

Underweight: BMI < 18.5
Normal weight: BMI 18.5–24.9
Overweight: BMI 25–29.9
Obesity: BMI ≥ 30

Note: BMI is a screening tool, not a diagnostic tool. It doesn't account for muscle mass, bone density, or distribution of fat.

BMR Calculator

The Basal Metabolic Rate (BMR) estimates the number of calories your body needs to perform basic functions like breathing, circulation, and cell production while at complete rest.

BMR Formula (Mifflin-St Jeor Equation)

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

Our BMR calculator uses this formula to estimate your body's calorie needs at rest. This is a starting point for determining your total daily energy expenditure (TDEE).

TDEE Calculator

The Total Daily Energy Expenditure (TDEE) estimates the total number of calories you burn each day, including activity and digestion.

TDEE Formula

TDEE = BMR × Activity Factor

Activity factors:

Sedentary: 1.2
Lightly active: 1.375
Moderately active: 1.55
Very active: 1.725
Athlete: 1.9

Our TDEE calculator combines your BMR with your activity level to provide a more accurate estimate of your daily calorie needs.

Body Fat Calculator

Body fat percentage is a measure of the amount of fat in your body relative to your total weight. It's an important indicator of overall health and fitness.

Body Fat Formula (US Navy Method)

For men: Body Fat % = 86.010 × log10(abdomen - neck) - 70.041 × log10(height) + 36.76

For women: Body Fat % = 163.205 × log10(abdomen + hip - neck) - 97.684 × log10(height) - 78.387 × log10(age) + 4.15

Our body fat calculator uses these formulas to estimate your body fat percentage based on measurements of your neck, waist, hips, height, and age.

Waist-to-Hip Ratio

The waist-to-hip ratio (WHR) is a simple calculation that compares your waist measurement to your hip measurement. It's often used as an indicator of health risks.

WHR Formula

WHR = Waist Circumference / Hip Circumference

Our WHR calculator helps you determine your waist-to-hip ratio. The results are generally interpreted as follows:

Healthy: WHR < 0.9 for women, < 1.0 for men
Moderate risk: WHR 0.9–1.0 for women, 1.0–1.1 for men
High risk: WHR > 1.0 for women, > 1.1 for men

FAQ

What are the limitations of BMI?

BMI doesn't account for muscle mass, bone density, or the distribution of fat in the body. It may not be accurate for athletes, older adults, or people with certain medical conditions.

How accurate are BMR and TDEE calculations?

BMR and TDEE estimates are generally accurate within 10-20% for most people. Individual variations can occur due to genetics, hormones, and other factors.

What is a healthy body fat percentage?

Healthy body fat percentages vary by age, sex, and body type. Generally, essential fat ranges from 2-5% for men and 10-13% for women, while athletic ranges are lower.

How often should I recalculate my health metrics?

It's recommended to recalculate your metrics every few months, especially if you're changing your diet, exercise routine, or have significant weight changes.