BMI Calculator – Body Mass Index for Adults
Calculate adult BMI from height and weight using metric or imperial units. See the formula-based category and weight range as a general reference.
BMI Categories
| Category | BMI Range |
|---|---|
| Severe Thinness | < 16 |
| Moderate Thinness | 16 - 17 |
| Mild Thinness | 17 - 18.5 |
| Normal | 18.5 - 25 |
| Overweight | 25 - 30 |
| Obese Class I | 30 - 35 |
| Obese Class II | 35 - 40 |
| Obese Class III | > 40 |
BMI is a screening tool and does not diagnose health. It does not account for muscle mass, bone density, or body composition. Consult a healthcare professional for personalized advice.
Calculate adult BMI from height and weight using metric or imperial units. See the formula-based category and weight range as a general reference.
What is body mass index?
What is body mass index?
Body mass index, or BMI, is a ratio of weight to height used as a general adult reference. The metric formula is weight in kilograms divided by height in meters squared. This calculator accepts metric and imperial measurements and displays the same ratio after unit conversion. BMI does not measure body fat, muscle or fitness. Two people can have the same BMI with different body composition, so the result should be read together with the explanation of its limits.
Ways to use the BMI calculator
Ways to use the BMI calculator
Calculate an adult reference value
Use a known height and weight to understand how the BMI formula works. The category is a reference label from the ratio, not an individual assessment of health.
Work with metric or imperial measurements
Calculate from centimeters and kilograms or feet, inches and pounds without doing the unit conversion separately. The two modes use the same underlying formula.
Understand the displayed weight range
See how multiplying height squared by the reference BMI bounds produces the weight range. This explains the display; it does not establish a personal goal weight.
How to calculate BMI in kg/cm or feet/pounds
How to calculate BMI in kg/cm or feet/pounds
Choose metric units to enter height in centimeters and weight in kilograms. Choose imperial units to enter height in feet and inches and weight in pounds. The result updates as you type. For example, 70 kg at 175 cm gives 70 ÷ 1.75² ≈ 22.9. Read the BMI number, its adult reference category and the formula-based weight range. Enter each measurement in the units shown beside its field; changing the unit selector requires checking the values again.
Tips for accurate inputs and sensible interpretation
Tips for accurate inputs and sensible interpretation
Use the correct height unit
In metric mode, enter 175 for a height of 1.75 meters. In imperial mode, put feet and additional inches in their separate fields rather than entering a decimal foot value.
Compare consistent measurements
If you revisit the tool, use comparable height and weight measurements and the same units. Rounding the inputs can change the last decimal or a category near a boundary.
Keep the adult scope in mind
This page does not use age, sex or growth charts. It does not provide BMI-for-age assessment for children or a tailored interpretation for pregnancy, athletes or individual medical history.
How to read the adult BMI categories
How to read the adult BMI categories
| Unrounded BMI | Reference category shown by the tool |
|---|---|
| < 16 | Severe Thinness |
| 16 – < 17 | Moderate Thinness |
| 17 – < 18.5 | Mild Thinness |
| 18.5 – < 25 | Normal |
| 25 – < 30 | Overweight |
| 30 – < 35 | Obese Class I |
| 35 – < 40 | Obese Class II |
| ≥ 40 | Obese Class III |
BMI calculation in your browser
BMI calculation in your browser
Enter measurements on a phone, tablet or desktop and read the result on the same page. The formula is calculated in the browser without an account. If no result appears, check that both height and weight are positive numbers and that the fields match the selected unit system.
What to check before using the result
What to check before using the result
BMI uses height and weight only. This calculator does not assess body composition, health history or children’s growth and does not provide an individual diagnosis.