Client-Side Tool • 100% Free & Private

Free Online BMI Calculator

Calculate adult BMI in metric or imperial units with standard categories. BMI is a screening measure, not a diagnosis; children need age-specific percentiles.

🔒 Browser processing

Your input never leaves your device.

✓ No signup✓ Free✓ Mobile friendly✓ Private

Loading BMI Calculator...

Everything runs 100% locally in your browser. No files are uploaded to any server.

Formula

Metric: BMI = weight in kilograms ÷ height in meters². Imperial: BMI = 703 × weight in pounds ÷ height in inches². Adult category bands are under 18.5, 18.5 to below 25, 25 to below 30, and 30 or above.

Worked example

At 70 kg and 1.75 m, BMI = 70 ÷ (1.75 × 1.75) ≈ 22.9. The same calculation in imperial units is approximately 703 × 154 ÷ 69² ≈ 22.7; the small difference comes from rounded example conversions.

What the result means

BMI is a general adult screening measure. It does not diagnose a condition or account for individual factors such as body composition, age, or pregnancy; discuss health questions with a qualified clinician.

How to Use BMI Calculator

Step 1

Choose Unit

Select Metric (kg/cm) or Imperial (lbs/ft).

Step 2

Enter Height & Weight

Type your measurements.

Step 3

Read Score

View BMI category and healthy weight target.

Key Features & Benefits

✓

Adult screening categories

Uses standard adult BMI cutoffs; BMI is only one measure considered when assessing health.

✓

Height-based reference range

Shows the weight range corresponding to adult BMI 18.5 to below 25, not a personalized health target.

Frequently Asked Questions

What is the adult BMI healthy weight range?

The standard adult BMI healthy weight range is 18.5 to below 25. BMI is a screening measure, not a diagnosis or a complete assessment of health.

Is this BMI result suitable for children?

No. Children and teens require age- and sex-specific BMI percentiles; this adult-category calculator does not provide them.

Does BMI account for muscle or body composition?

No. BMI uses height and weight only and does not distinguish muscle, bone, or fat mass.

Key terms

BMI: Body Mass Index, calculated from height and weight. For adults it is a screening measure to consider alongside other health information, not a diagnosis.

How adult BMI is calculated

Metric BMI divides weight in kilograms by height in meters squared. For 70 kg and 1.75 m, 70 ÷ (1.75 × 1.75) is about 22.9. The imperial calculation uses pounds and inches with a conversion factor of 703.

The displayed adult categories are screening bands: below 18.5, 18.5 to below 25, 25 to below 30, and 30 or above. The reference weight range on this page corresponds to the adult BMI band 18.5 to below 25; it is not a personalized target.

When BMI is not the right answer

BMI uses only height and weight. It does not measure muscle, fat distribution, pregnancy-related changes, or health conditions. Two people with the same BMI can have very different health profiles.

This adult-category tool does not provide the age- and sex-specific percentiles used for children and teens. A BMI result is not a diagnosis. Discuss a health concern or weight goal with a qualified clinician.

Related Tools

Age Calculator