BMI Calculator — Body Mass Index

Free, private BMI calculator. Calculate your Body Mass Index with metric or imperial units. Visual BMI scale, category classification, healthy weight range — 100% client-side. 100% serverless.

🔒 100% Private
Completely Free
🌐 Runs in Browser
📦 Export Ready

BMI Calculator — Body Mass Index

Tool Workspace

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  1. Choose units — Metric (kg/cm) or Imperial (lbs/ft).
  2. Enter weight and height.
  3. Click Calculate to see your BMI, category, and healthy weight range.
  4. Review the visual scale showing where your BMI falls.

What Is the BMI Calculator?

The BMI Calculator is a free tool for calculating your Body Mass Index — a widely used measure of body weight relative to height. Enter your weight and height in metric or imperial units, and instantly see your BMI value, weight category, and healthy weight range. A visual color-coded scale shows exactly where your BMI falls.

Key Features

  • Metric & Imperial — Switch between kg/cm and lbs/feet with one click.
  • Visual BMI Scale — Color-coded gradient bar with animated marker showing your BMI position.
  • Category Classification — Underweight, Normal, Overweight, Obese (Classes I-III).
  • Healthy Weight Range — Shows the ideal weight range for your height.
  • Medical Disclaimer — Reminds users that BMI is a screening tool, not a diagnosis.
  • 5-Language Support — English, Arabic, Spanish, Portuguese, Chinese.
  • 100% Client-Side — No data is sent to any server.

How BMI Is Calculated

BMI = weight (kg) ÷ height (m)². For example, a person weighing 70 kg and 175 cm tall has a BMI of 70 ÷ (1.75)² = 22.86 (Normal Weight).

BMI Categories

BMI RangeCategory
< 18.5Underweight
18.5 – 24.9Normal Weight
25 – 29.9Overweight
30 – 34.9Obese (Class I)
35 – 39.9Obese (Class II)
≥ 40Obese (Class III)

Privacy & Security

This tool runs 100% in your browser. No health data is ever sent to a server.

Frequently Asked Questions

Is my health data safe?

Yes. All calculations happen 100% in your browser. No data is sent to any server. Your health information stays entirely on your device.

What is a normal BMI?

A BMI between 18.5 and 24.9 is considered normal weight. Below 18.5 is underweight, 25-29.9 is overweight, and 30+ is classified as obese.

Is BMI accurate for everyone?

BMI is a useful screening tool but has limitations. It doesn't account for muscle mass, bone density, or body composition. Athletes with high muscle mass may have elevated BMI scores. Consult a healthcare professional for complete assessment.

Does it support imperial units?

Yes. Toggle between Metric (kg, cm) and Imperial (lbs, feet/inches) with one click.

What age range does it support?

The calculator works for adults aged 18 and older. BMI interpretation differs for children and adolescents.

How is BMI calculated?

BMI = weight (kg) / height (m)². For imperial units, the tool converts to metric before calculating.