Decision tools built for clarity
BMI Calculator
Estimate adult body mass index for educational use.
Choose metric or US units, then enter an adult weight and height.
This adult BMI screening estimate is educational, non-diagnostic, and not for children, adolescents, or pregnancy; consult a qualified health professional.
Methodology
Formula or transformation
Divides adult weight in kilograms by squared height in meters and maps the result to educational adult thresholds.
Variables
- Weight normalized to kilograms
- Height normalized to meters
- Calculated body mass index
- Adult BMI category thresholds
Units
- Kilogram
- Meter
- Kilograms per square meter
Rounding policy
BMI is rounded to the declared result scale using half away from zero before display.
Adult BMI divides weight in kilograms by height in metres squared and compares the result with adult screening categories.
Estimate adult body mass index for educational use.
Reviewed sources
- CDC — Adult BMI categories Reviewed on 2026-09-04
- CDC — Calculating body mass index Reviewed on 2026-09-04
Formula review history
-
Initial formula and source review.
Reviewed 2026-09-04 for formula version adult-bmi-v1
Assumptions
- The inputs describe an adult and use the selected unit system.
- Height and weight are measured accurately at the time of calculation.
Limitations
- Adult BMI is a screening measure and does not diagnose health or directly measure body fat.
- It is not the appropriate child or adolescent assessment and may misclassify pregnancy, athletes, older adults, or some populations.
Worked example
An adult weighing 70 kg at 1.75 m has BMI 70 ÷ 1.75² = 22.86, within the 18.5–24.9 adult screening range.
Frequently asked questions
Does BMI diagnose a condition?
No. A clinician considers BMI alongside history, measurements, and other evidence.
Can this adult calculator assess a child?
No. Children and adolescents require age-and-sex-specific growth-chart assessment.