BMI Calculator

BMI Calculator

Are you at a healthy weight for your height?

Unit System

About BMI Calculator

Body Mass Index (BMI) is a screening measure that estimates whether a person has a healthy body weight relative to their height. The formula was standardised by WHO in 1997 and remains the international benchmark for population-level weight assessment. It is a screening tool — not a diagnostic one — and should always be considered alongside other clinical measures.

Formula
Metric:   BMI = weight (kg) ÷ height² (m)
Imperial: BMI = [weight (lbs) ÷ height² (in)] × 703
Severe Thinness< 16.0
Moderate Thinness16.0 – 16.9
Mild Thinness17.0 – 18.4
Normal weight18.5 – 24.9
Pre-obesity25.0 – 29.9
Obesity Class I30.0 – 34.9
Obesity Class II35.0 – 39.9
Obesity Class III≥ 40.0
BMI is a population screening tool, not a diagnostic measure. It does not distinguish fat from muscle mass, does not capture fat distribution, and varies in accuracy by sex and age. WHO recommends waist circumference (>102 cm in men, >88 cm in women) as a complementary measure. For Asian populations, WHO identifies increased cardiometabolic risk starting at BMI 23.0.

Source: WHO Global Classification (1997) · WHO Obesity Fact Sheet (2022) · WHO Expert Consultation on BMI for Asian Populations, The Lancet (2004) · NHLBI Clinical Guidelines

Why Your BMI Result Matters

Awareness is the first step toward better health. Research from WHO and NHLBI consistently links sustained overweight (BMI ≥ 25) and obesity (BMI ≥ 30) to a higher likelihood of the following conditions. Recognising these connections early gives you the opportunity to take informed, preventive action.

01

Cardiovascular Disease

Obesity is a leading driver of heart disease worldwide. Reaching a healthy BMI reduces arterial inflammation, improves cholesterol levels, and significantly lowers the risk of heart attack and stroke.

02

Type 2 Diabetes

Excess visceral fat is the primary modifiable risk factor for type 2 diabetes. Studies show that losing just 5–10% of body weight can delay or prevent onset in at-risk individuals.

03

Hypertension

Higher body mass directly increases the workload on the heart. Even modest, sustained weight loss produces clinically meaningful reductions in blood pressure.

A healthy BMI is a two-way target. Being underweight (BMI < 18.5) is equally important to address — it is associated with reduced bone density, weakened immunity, and nutritional deficiencies. Every step toward the 18.5–24.9 range is a step toward better health.

How to Use BMI Most Effectively

BMI is a powerful starting point — not the complete picture. WHO and CDC both classify it as a screening tool, not a diagnostic one. Understanding where it works best helps you get the most value from your result:

01

Combine with waist circumference

BMI does not show where fat is stored. Waist circumference (>102 cm in men, >88 cm in women) identifies visceral fat risk that BMI misses. Using both together gives a significantly stronger health signal than either measure alone.

02

Athletes and muscular individuals: add a body fat reading

Muscle is denser than fat. If you train regularly, your BMI may read 'overweight' while your body fat is low. Pair your result with a body fat percentage measurement for an accurate picture of your composition.

03

BMI is a screening start, not a medical verdict

A BMI result alone cannot diagnose any condition. For a complete picture, your doctor will assess waist circumference, blood pressure, blood glucose, lipid panel, and lifestyle together with your BMI.

Frequently Asked Questions