BMI Calculator - Body Mass Index & Healthy Weight Range
Calculate adult body mass index from height and weight, then compare the result with common BMI categories and an estimated healthy weight range.
Your Measurements
Enter your height and weight.
BMI Scale
Underweight
< 18.5
Normal
18.5 - 24.9
Overweight
25 - 29.9
Obese I
30 - 34.9
Obese II+
35+
Your BMI
Body Mass Index result.
Body Mass Index
23.6
Normal weightBMI is a screening tool, not a diagnostic measure. Consult a healthcare provider for personalised guidance.
Methodology and limitations
Last reviewed:
Methodology
Calculates adult BMI as weight (kg) ÷ height (m)² using standard WHO/CDC category thresholds for adults 20 and older.
Limitations
BMI does not measure body fat directly and may misclassify muscular or elderly individuals. Not intended for children, pregnant women, or clinical diagnosis.
Official sources
How to Calculate Adult BMI
Calculate adult body mass index from height and weight, then compare the result with common BMI categories and an estimated healthy weight range.
Method used
The calculator converts height and weight to metric units when needed, then calculates body mass index and compares it with common adult BMI categories.
BMI = weight in kilograms / (height in meters x height in meters)
Practical example
An adult who is 5 feet 9 inches tall and weighs 160 pounds has a BMI of about 23.6, which falls in the common healthy weight category.
- Height: 5 ft 9 in
- Weight: 160 lb
- Unit system: imperial
The result shows BMI, weight category, and an estimated healthy weight range for the entered height.
Assumptions
- The BMI categories are adult screening categories.
- Height and weight are user-entered measurements.
- BMI is an estimate and is not a medical diagnosis.
What this includes
- Imperial and metric inputs, BMI value, adult BMI category, and estimated healthy weight range.
What this excludes
- Child BMI percentiles, pregnancy, clinical diagnosis, body-fat measurement, muscle mass, ethnicity-specific risk, and medical history.
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Frequently Asked Questions
What is BMI?
BMI, or body mass index, is a screening measure that compares weight with height using weight divided by height squared. It can estimate weight category for many adults, but it is not a diagnosis of health, fitness, or body fat. Pair BMI with waist size, symptoms, labs, and clinical judgment when making decisions. This calculator is an educational screening estimate only.
What BMI range is usually considered healthy for adults?
The CDC adult BMI categories list 18.5 to 24.9 as the healthy weight range for most adults, with underweight below 18.5, overweight from 25 to 29.9, and obesity at 30 or higher. Category cutoffs are population guidelines, not personal health diagnoses. Some adults outside that range are metabolically healthy, and some inside it are not—use BMI as one data point with your clinician.
Is BMI accurate for everyone?
No. BMI does not directly measure body fat, muscle mass, pregnancy status, ethnicity-specific risk patterns, or medical history. Very muscular people, older adults with low muscle, and some ethnic groups may be miscategorized. Use it as a quick screening estimate only, and ask a healthcare professional when BMI results conflict with how you feel or other clinical measures.
Can athletes have a high BMI and still be healthy?
Yes. Muscle weighs more than fat, so very muscular people may fall into the overweight BMI range despite low body fat and strong cardiometabolic markers. A body composition assessment, waist circumference, or clinical exam may be more informative than BMI alone for athletes. Treat high BMI in trained individuals as a prompt to look deeper, not an automatic health problem.
Should I use BMI if I am pregnant?
Standard adult BMI is not designed for pregnancy because weight gain is expected and clinically managed differently. Pregnant individuals should follow prenatal weight guidance from their healthcare provider instead of adult BMI categories. Pre-pregnancy BMI is sometimes used for counseling, but day-to-day pregnancy weight goals belong in prenatal care, not this adult screening tool.