ConverterBMI Calculator
Calculate BMI from metric height and weight. The numeric result is available for any valid positive inputs; CDC adult categories are shown only when you explicitly select the age-20-or-older interpretation.
Metric BMI Formula
CDC Adult Screening Categories
| Unrounded BMI | Category |
|---|---|
| Below 18.5 | Underweight |
| 18.5 to below 25 | Healthy Weight |
| 25 to below 30 | Overweight |
| 30 or higher | Obesity |
What The Number Does Not Measure
BMI does not distinguish muscle, fat, bone, pregnancy, or fat distribution. It is a screening value rather than a direct body-fat measurement.
For a child or teenager, use an age- and sex-specific growth-chart process instead of these adult categories. Medical interpretation belongs with a qualified health professional.
How The BMI Calculation Works
The metric formula is BMI = weight in kilograms / (height in meters x height in meters). A height entered in centimeters must first be divided by 100. For example, 175 cm becomes 1.75 m before the height is squared.
The imperial formula is BMI = 703 x weight in pounds / (height in inches x height in inches). This page currently expects metric input, so convert pounds to kilograms or inches to centimeters before entering an imperial measurement.
Adult BMI Screening Categories
| BMI | Screening Category | Interpretation Note |
|---|---|---|
| Below 18.5 | Underweight | A screening flag that needs individual context |
| 18.5 to 24.9 | Healthy range | A common reference range for adults |
| 25.0 to 29.9 | Overweight | Does not distinguish fat from muscle |
| 30.0 or above | Obesity range | Clinical context is still required |
Worked BMI Examples
| Weight | Height | Calculation | BMI |
|---|---|---|---|
| 70 kg | 175 cm | 70 / 1.75 squared | 22.9 |
| 90 kg | 180 cm | 90 / 1.80 squared | 27.8 |
| 60 kg | 165 cm | 60 / 1.65 squared | 22.0 |
Limits And Common Mistakes
- Do not enter centimeters as meters. Entering 175 as meters would make the result meaningless.
- Do not compare adult BMI categories directly with child or teen growth assessment methods.
- Do not assume a muscular athlete and a sedentary adult with the same BMI have the same body composition.
- Use consistent measurement conditions when tracking change, and keep the original height and weight beside the result.
- Ask a qualified health professional about individual risk, symptoms, treatment, or diagnosis.
Related Measurement Tools
- Convert kilograms to pounds - useful when a weight record is in imperial units
- Convert pounds to kilograms - prepare a weight value for the metric BMI input
- Check centimeters in inches - compare height records across unit systems
- Convert inches to centimeters - prepare an imperial height for metric input
Tool-Specific Accuracy Notes
BMI Calculator is built for quick planning and verification, but the result is only as reliable as the input values and assumptions used on the page.
- Keep the original inputs with any copied result so the calculation can be reviewed later.
- Use this calculator for pre-checks, estimates, and workflow support, not as a replacement for official review.
- Recalculate after correcting dates, units, decimal places, or eligibility cutoffs.
Frequently Asked Questions
Enter weight in kilograms and height in centimeters, separated by a space, such as 70 175.
It uses BMI = kilograms divided by height in meters squared. The centimeter input is converted to meters before calculation.
No. BMI is a screening measure and does not directly measure body fat, muscle, fitness, or individual medical risk.
BMI uses total weight and height, so it cannot distinguish muscle mass from fat mass.
No. Children and teens are assessed with age- and sex-specific growth references rather than the adult cutoffs shown here.
Use consistent units and similar measurement conditions, and keep the original height and weight with each result.
Learn More About This Topic
Use the supporting guide to interpret the number carefully and keep BMI separate from a medical diagnosis. For more context, read what a BMI result can and cannot show before using the result in a real workflow.