Health & Fitness
BMI Calculator
Calculate your Body Mass Index (BMI) using metric (cm/kg) or imperial (ft-in/lb) units, plus your WHO weight category. General screening tool only.
Your BMI
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Underweight Normal Overweight Obese
Important: BMI is a general screening tool based on height and weight only — it does
not account for muscle mass, bone density, body composition, age, or sex. It is not a diagnosis. Consult a
doctor or qualified healthcare provider for a full health assessment.
What is my BMI, and what category is that?
BMI = weight (kg) ÷ height (m)², or the US customary equivalent. Categories (underweight / normal / overweight / obesity) follow common CDC adult cutoffs. BMI is a screening number — it does not know muscle, bone, or where you carry fat.
Use it as a flag, not a diagnosis
Athletes and older adults are often mis-sorted. For calories, see calorie needs. This is not medical advice.
Frequently Asked Questions
What is BMI?
Body Mass Index (BMI) is a simple screening measure that uses your height and weight to estimate whether you're in an underweight, normal weight, overweight, or obese range, according to World Health Organization (WHO) categories.
How is BMI calculated?
BMI = weight (kg) / height (m) squared. For imperial units, height and weight are first converted to metric before applying the same formula.
What are the BMI categories?
Under 18.5 is Underweight, 18.5-24.9 is Normal weight, 25-29.9 is Overweight, and 30 and above is Obese, according to the standard WHO classification used worldwide.
Is BMI an accurate measure of health?
BMI is a useful general screening tool for populations, but it has real limitations for individuals — it doesn't distinguish between muscle and fat mass, so athletes and very muscular people can show a high BMI despite low body fat. It's not a diagnostic tool.
Does BMI account for age or sex?
The standard adult BMI formula and categories used here do not adjust for age or sex. Some clinical contexts use different reference ranges for children, older adults, or specific populations — consult a doctor for a more personalized assessment.
What should I do if my BMI is outside the normal range?
BMI alone doesn't determine your health status. If you have concerns about your weight or BMI result, consult a doctor or qualified healthcare provider, who can consider your full health picture, not just height and weight.
How do I calculate BMI in imperial units by hand?
BMI = 703 x weight (lb) / [height (in)]². For example, a 154 lb person at 5'7" (67 inches): 703 x 154 / 67² = 703 x 154 / 4489 ≈ 24.1.
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About these results: Figures are for planning only. Confirm anything you will buy, bill, or submit (materials, payroll, medical screening) against the label, a quote, or a professional.