Body Mass Index (BMI) is a screening ratio of weight to height that helps classify underweight, normal weight, overweight and obesity for adults.

How do I calculate BMI?

BMI = weight (kg) / [height (m)]^2. For pounds and inches: BMI = 703 × weight (lb) / [height (in)]^2.

What is a healthy BMI?

For most adults: 18.5–24.9 is considered the normal range. Below 18.5 is underweight, 25.0–29.9 overweight, and 30+ obesity.

Is BMI accurate for everyone?

BMI is a rough screening tool and may misclassify athletes, pregnant individuals, and people with atypical body compositions. Consult a clinician for diagnosis.

BMI

BMI Calculator

Fast & accurate Body Mass Index calculator with healthy weight range, chart, formula & FAQs. Works offline.

Calculate your BMI

Unit system

Age (optional)

Sex (optional)

Height (cm)

Enter height between 30 and 300 cm.

Weight (kg)

Enter weight between 10 and 500 kg.

Your BMI

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Healthy weight range for your height

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Based on adult BMI 18.5–24.9. Not for children, pregnancy, or certain conditions.

BMI Prime (BMI ÷ 25)

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Scale reference: <18.5 Underweight · 18.5–24.9 Normal · 25–29.9 Overweight · 30–34.9 Obesity I · 35–39.9 Obesity II · ≥40 Obesity III

BMI Chart & Reference

Category	BMI (kg/m²)
Underweight	< 18.5
Normal	18.5 – 24.9
Overweight	25.0 – 29.9
Obesity I	30.0 – 34.9
Obesity II	35.0 – 39.9
Obesity III	≥ 40.0

BMI Formula

Metric: BMI = weight (kg) ÷ [height (m)]²

US: BMI = 703 × weight (lb) ÷ [height (in)]²

BMI is a screening tool. It doesn’t measure body fat directly and may misclassify athletes or people with high muscle mass. Seek clinical advice for diagnosis.

Quick QA

What is BMI?

Body Mass Index relates weight to height to estimate whether your weight is within a typical range for adults.

Is BMI enough to judge health?

No. Consider waist size, body composition, lifestyle, and clinical markers. BMI is a starting point, not a diagnosis.

What is BMI Prime?

BMI Prime = BMI ÷ 25. Values < 1 indicate below the upper normal boundary; > 1 indicate above.

Automated Tests

A few sanity checks at 170 cm across different weights.