BMI Calculator

About BMI Calculator

Body mass index compares weight with height and is used as a general screening number. Choose imperial or metric units, enter your weight and height, and the calculator shows your BMI and a category. BMI does not measure body fat, muscle or overall health and may be less accurate for athletes, older adults and children. This tool is not medical advice, so talk to a healthcare professional about your health.

Example

Input: 160 lb and 5 ft 9 in. Output: a BMI around 23.6 in the healthy range.

Tips for better results

• Use BMI as one data point, not a diagnosis.
• Children and teens use different charts.
• Discuss results with a doctor.

When to use BMI Calculator

The BMI Calculator offers a quick screening number for adults who want to see how their weight compares with their height. People starting a fitness plan, filling in a wellness form or wanting a simple reference point can use it. Choose metric or imperial units, enter your numbers and read the category. It is only a rough guide and does not measure body fat or fitness, so use it as one piece of information and speak with a healthcare professional about your health.

Real-world uses

• Someone starting a new exercise routine records a baseline BMI alongside other measurements like waist size and energy levels.
• A person filling out a wellness program form needs a quick BMI figure and checks it using their own height and weight.
• A user switching between pounds and kilograms confirms that the metric and imperial results agree for the same body measurements.
• A parent curious about adult BMI categories learns how the calculation works before discussing questions with a doctor.

Common mistakes to avoid

• Using a rounded or guessed height changes the result noticeably. Measure height and weight carefully, and enter values in the unit you selected.
• Treating the category as a verdict about health is a mistake. BMI ignores muscle, bone structure, age and many other factors that matter.
• Using the adult chart for children and teens gives misleading results. Young people are assessed with growth charts that account for age and sex.

Calculate body mass index in metric or imperial units. It works instantly in your browser, so there is nothing to install and nothing to upload. BMI Calculator is part of our collection of 100 free tools in the Daily Life & Money category.

How to use it

1. Enter your information or choose a file in the tool above.
2. Your result appears right below the tool.
3. Copy the result, or adjust your input and try again.

Frequently asked questions

Why do metric and imperial give the same result?

Both use the same underlying formula, with unit conversions built in. Small differences can appear from rounding, but the BMI value should be very close for the same measurements.

Should I change my lifestyle based on this number?

Do not make health decisions from BMI alone. It is a screening number, not a diagnosis. A doctor or other qualified professional can consider your full situation and give personal guidance.

Is BMI Calculator free to use?

Yes. BMI Calculator is completely free and you do not need to create an account.

Is my data uploaded anywhere?

No. This tool runs in your browser, so what you type or choose stays on your device.

How accurate are the results?

Calculations use standard formulas, but always double-check important figures, especially for money, health or legal decisions.