BMI Calculator

Calculate your Body Mass Index, body fat percentage, and healthy weight range. Supports metric and imperial units with progress history.

Body Mass Index (BMI) is a quick screening tool used by health professionals to categorize individuals based on weight relative to height. Enter your measurements in either metric or imperial units, and this calculator instantly shows your BMI, weight category, body fat percentage (using the Navy method), a color-coded visual scale, and the healthy weight range for your height. All processing happens locally in your browser — no data is stored or transmitted. Save your results to track progress over time.

Height (cm)

Weight (kg)

Age

Sex

Waist (cm)

Height (ft)

Height (in)

Weight (lbs)

Age

Sex

Waist (in)

Enter Calculate Esc Clear Ctrl+S Copy

Measurement History

BMI Categories Explained

Understanding what each BMI category means helps you interpret your results in context. BMI is a screening tool, not a diagnosis — here's what the numbers actually indicate.

Underweight (BMI < 18.5)

Being underweight can indicate malnutrition, eating disorders, or other health issues. It may also be associated with weakened immune function, osteoporosis, and fertility problems. If your BMI is below 18.5, consider consulting a healthcare provider to rule out underlying conditions.

Normal Weight (BMI 18.5–24.9)

This range is associated with the lowest risk of weight-related health problems. People in this category generally have a healthy balance of body fat and muscle mass. Maintaining a BMI in this range through balanced nutrition and regular physical activity supports overall health.

Overweight (BMI 25.0–29.9)

Being overweight increases the risk of heart disease, type 2 diabetes, high blood pressure, and certain cancers. Small lifestyle changes — like improving diet quality and increasing physical activity — can help bring BMI into the normal range. Even modest weight loss (5-10% of body weight) can significantly improve health markers.

Obese (BMI 30.0+)

Obesity is associated with significantly higher risk of serious health conditions including heart disease, stroke, type 2 diabetes, and certain cancers. Medical interventions, structured weight management programs, and lifestyle changes can help. BMI is a starting point for discussion with a healthcare provider about appropriate next steps.

Quick Answer

BMI Calculator is a Calculate Body Mass Index with metric and imperial units. Includes BMI category, healthy weight range, and visual gauge. by ThinkaBell. It runs all processing happens locally in your browser — no sign-up, no file uploads, and no data ever leaves your device.

Feature: Supports metric (kg/cm) and imperial (lbs/ft/in) units
Feature: Shows BMI category: Underweight, Normal, Overweight, Obese
Feature: Displays healthy weight range for your height
Feature: Visual gauge for quick BMI interpretation
Feature: Privacy-first — all calculations happen in your browser
Feature: Completely free with no account required
Feature: Works on desktop, tablet, and mobile browsers
Feature: No data sent to servers — your measurements stay on your device
Privacy-first: no data collection, no tracking, no uploads.
Free forever: no premium tiers, no hidden charges, no accounts.

Key Terms

Web Application: A web application that runs entirely in your browser using HTML, CSS, and JavaScript. No software installation, no account creation, and no file uploads to external servers.
Client-Side Processing: All calculations and data processing happen on your device. Your information never leaves your browser, ensuring complete privacy and security.
Calculators: A utility accessible through a web browser at no cost. ThinkaBell tools are free with no premium tiers, no usage limits, and no account requirements.