BMI Calculation Explained " With Chart for Men & Women (2026)
BMI (Body Mass Index) is the world's most widely used health screening tool. Doctors and health professionals use it to quickly assess whether a person's weight is healthy relative to their height. In this guide you'll learn the exact BMI formula, how to calculate your BMI step by step, and how to read the official BMI chart for both men and women.
Imperial: BMI = (Weight lbs Height inches) — 703
→ Use Free BMI Calculator " Instant Result
What is BMI?
Body Mass Index (BMI) is a numerical value derived from a person's weight and height. It was developed in the 1830s by Belgian mathematician Adolphe Quetelet. Despite its simplicity, it remains the standard global screening metric because it is free, non-invasive, and reasonably accurate for population-level assessment.
The BMI Formula
Imperial: BMI = [Weight (lbs) / Height (inches)] — 703
Step-by-Step Calculation Example
Person: Weight = 75 kg | Height = 1.72 m
Step 1: Square the height → 1.72 — 1.72 = 2.9584
Step 2: Divide weight by result → 75 2.9584 = BMI = 25.4
Result: BMI of 25.4 = Overweight category.
BMI Classification Chart (WHO Standards)
| BMI Range | Category | Health Risk |
|---|---|---|
| Below 18.5 | Underweight | Moderate |
| 18.5 " 24.9 | Normal / Healthy | Low (best range) |
| 25.0 " 29.9 | Overweight | Increased |
| 30.0 " 34.9 | Obese Class I | High |
| 35.0 " 39.9 | Obese Class II | Very High |
| 40.0+ | Obese Class III | Extremely High |
BMI Limitations " What It Doesn't Measure
- Does not distinguish between muscle and fat (athletes may show "overweight" BMI)
- Does not account for age " older adults naturally have more fat
- Does not measure fat distribution (belly fat vs thigh fat)
- ✅ Use BMI alongside waist circumference and body fat % for a better picture
Check Your BMI Free
Free BMI Calculator " Instant Result
Enter your weight and height in metric or imperial units. Get your BMI score, category, and healthy weight range instantly.
Open BMI Calculator →After checking your BMI, use our Calorie Calculator to find your daily calorie needs based on your activity level.
FAQs
Is BMI the same for men and women?
The BMI formula is the same for both, but women naturally carry more body fat than men at the same BMI. This is normal and the healthy range (18.5"24.9) applies to both genders.
What BMI is considered obese?
A BMI of 30 or above is classified as obese by WHO standards. A BMI of 40 or above is morbidly obese and associated with serious health risks.