BMI Calculator

Calculate your Body Mass Index from height and weight instantly — free, private, and right in your browser.

Overview

What is a BMI calculator?

A BMI calculator estimates Body Mass Index by dividing your weight by the square of your height, producing a single number that's compared against standard ranges to place you into a category — underweight, normal weight, overweight, or obese.

It's used worldwide as a fast, free screening tool by individuals, clinicians, and researchers alike. While it doesn't measure body fat directly, it remains one of the simplest ways to get a general sense of whether weight falls within a typical healthy range for a given height.

Guide

How to use it

Two fields, no learning curve — enter height and weight, get an instant result.

Step 01

Enter your height

Type your height in centimeters into the height field.

Step 02

Enter your weight

Type your weight in kilograms into the weight field.

Step 03

See your BMI instantly

Your Body Mass Index and category are calculated the moment both fields are filled in.

Tips

Best practices to keep in mind

A few things worth knowing about what BMI can and can't tell you.

BMI is a useful screening tool, but it doesn't measure body fat directly or account for muscle mass — a muscular athlete can show a high BMI while being perfectly healthy.
Don't use BMI alone to diagnose a health condition. It's one data point among many — waist circumference, body composition, and a doctor's assessment matter just as much.
BMI categories are based on general population averages and may not apply the same way to children, pregnant women, older adults, or very tall or short individuals.
Track BMI over time rather than fixating on a single reading. A gradual trend tells you far more about progress toward a health goal than any one snapshot.

Comparison

SEOJuicer vs. other BMI calculators

The same result, minus the uploads, the signup wall, and the paywall.

SEOJuicer

Runs entirely in your browser

Free, no signup required

Instant category breakdown

No data stored or sent anywhere

Unlimited calculations

Other tools

Often loaded with ads

May require an account

Just a raw number, no context

Sends data to a server

Slower, server-based results

FAQs

Frequently asked questions

Have questions about calculating BMI? Here are the most common ones our users ask before getting started.

Is this BMI calculator free to use?

Yes, the BMI calculator is completely free with no signup, no usage limits, and no hidden charges. It runs entirely in your browser using JavaScript, so no data ever leaves your device and no account is required to calculate your Body Mass Index.

How is BMI calculated?

BMI is calculated by dividing your weight in kilograms by the square of your height in meters. The result is a single number that's then compared against standard ranges to place you into a category — underweight, normal weight, overweight, or obese — giving a quick screening estimate of body weight relative to height.

What do the BMI categories actually mean?

A BMI under 18.5 is classed as underweight, 18.5 to 24.9 as normal weight, 25 to 29.9 as overweight, and 30 or above as obese. These ranges are population-level guidelines from health organizations and are meant as a starting point for a conversation about health, not a definitive individual diagnosis.

Is BMI an accurate measure of my health?

BMI is a useful, quick screening tool but it has known limitations — it doesn't distinguish between muscle and fat mass, so athletes and very muscular people can register a higher BMI despite low body fat. It also doesn't account for age, sex, or where fat is distributed on the body, so it should be considered alongside other health measures.

Does this tool store or share my height and weight?

No. The entire calculation happens locally in your browser — your height and weight figures are never transmitted to a server, logged, or stored anywhere. You can calculate your BMI privately as many times as you like without any personal health data being retained.

Explore

Browse other categories

Every category groups related tools together, all free and ready to use instantly.

SEO ToolsAudit, scan, and optimize any page to help it rank higher in search.Performance ToolsMeasure load time, compression, and mobile readiness for any page.Domain & Server ToolsInspect DNS, SSL, hosting, and server health in seconds.Content ToolsCheck content originality and detect AI-generated writing.