About the BMI Calculator
This free bmi calculator helps people in the United States get a quick, private estimate before they talk to a lender, insurer, employer or advisor. There is no signup, nothing is stored on our servers and every result updates instantly in your browser.
How this calculator works
BMI = 703 * weight in pounds / height in inches squared. Categories follow the CDC adult scale: under 18.5, 18.5 to 24.9, 25 to 29.9 and 30 or higher.
Worked example
160 lbs at 5 ft 9 in gives BMI 23.6, in the healthy range. Change any input above to see how the result moves, which is the fastest way to understand which factor matters most for you.
Tips to get a better result
BMI is a screening tool, not a diagnosis. It does not measure muscle, bone density or fat distribution. Talk to a doctor about your health.
Key factors that change your result
BMI uses only height and weight, so it cannot tell muscle from fat and may be less accurate for athletes, older adults and some ethnic groups. Use it as a screening number and talk to a doctor about your overall health.
Accuracy and limits
Every calculator on Tools30 uses standard published formulas combined with average US market assumptions. Real results depend on your personal circumstances, so treat the output as a starting point and confirm with a qualified professional. Read more on our methodology page.
Frequently asked questions
Is BMI accurate for athletes?
Not always, because muscle weighs more than fat.
Is this medical advice?
No. Consult a healthcare professional.
Is the bmi calculator free to use?
Yes. Every calculator on Tools30 is free with no registration.
Do you store the numbers I enter?
No. Calculations run in your browser and nothing you type is sent to our servers.