BMI Calculator

Calculate your body mass index, category, and healthy weight range estimate in seconds.

Last Updated: February 2026

Unit System

Height (Feet)

Height (Inches)

Weight (lbs)

Age

BMI categories are generally interpreted differently for children and teens.

Gender

BMI Value

0.0

BMI Category

Not calculated

Healthy Weight Range

BMI Scale

UnderNormalOverObese

Medical Disclaimer

This calculator is for informational purposes only and is not medical advice. BMI is a screening metric and not a diagnosis. Health decisions should be based on full clinical context and guidance from a licensed healthcare professional.

How This Calculator Works

The BMI calculator converts your height and weight into a standardized ratio. For metric input, it divides kilograms by meters squared. For US input, it applies the equivalent 703-based formula using pounds and inches.

It then assigns a category using widely used adult cutoffs and estimates a healthy-weight range corresponding to a BMI between 18.5 and 24.9 at your current height.

Use the output as a screening reference and conversation starter with your healthcare provider, not a stand-alone diagnosis.

What You Need to Know

What BMI helps with

BMI is useful as a fast population-level screening signal and a simple personal trend metric over time. It is easy to calculate and broadly understood, which makes it helpful for high-level monitoring.

For personal health decisions, BMI is one input among many. It should be interpreted with blood pressure, lipid profile, glucose data, activity level, sleep, and clinical history.

Limitations of BMI

BMI does not directly measure body fat percentage or fat distribution. A muscular person can have a higher BMI without elevated cardiometabolic risk, while someone with lower BMI can still carry risk factors that require attention.

Ethnicity, age, and body composition differences also matter. Clinical interpretation is always more nuanced than a single numeric threshold.

Healthy lifestyle context

Sustainable improvements usually come from consistent behavior: balanced eating patterns, resistance and aerobic activity, sleep quality, and stress management. Fast, extreme changes often reverse quickly.

If your goal is weight management, aim for gradual progress and track multiple indicators rather than BMI alone.

When to seek medical guidance

If you have chronic conditions, unexplained weight changes, medication-related weight effects, or concerns about eating patterns, speak with a clinician. Personalized guidance is essential when health risk or treatment planning is involved.

This tool can support awareness, but medical decisions should always be based on qualified professional evaluation.

Frequently Asked Questions

BMI (Body Mass Index) is a screening measure that relates weight to height. It is commonly used to classify underweight, normal weight, overweight, and obesity ranges for adults.

In metric units BMI = kg/m². In US units BMI = 703 × weight(lb) / height(in)².

No. BMI is a screening metric and does not directly measure body fat, muscle distribution, or individual metabolic health.

Standard adult BMI category thresholds are broadly shared, but overall health interpretation can differ by age, sex, body composition, and medical context.

For adults, a BMI from 18.5 to 24.9 is commonly classified as normal weight in major public-health references.

No. BMI should be interpreted with additional indicators such as waist measurements, labs, fitness, medical history, and clinician guidance.

Children and adolescents are typically assessed using age- and sex-specific BMI percentiles rather than adult fixed thresholds.

No. This tool is informational only and not a diagnostic instrument.