Find out whether your BMI falls into the Class III (morbidly obese) range. Enter height and weight for an instant BMI check plus the obesity class breakdown.
Body Mass Index (BMI) is a simple, widely-used screening tool that estimates body fat based on your height and weight. Developed in the 1830s by Belgian mathematician Adolphe Quetelet, BMI provides a quick way to categorize weight status and assess potential health risks.
This range is associated with the lowest risk of weight-related health problems. Maintaining a healthy BMI supports cardiovascular health, reduces diabetes risk, and promotes overall well-being.
This range indicates increased risk for conditions like high blood pressure, type 2 diabetes, and certain cancers. Modest weight loss (5-10%) can significantly improve health outcomes.
Obesity significantly increases risk for serious health conditions including heart disease, stroke, type 2 diabetes, and sleep apnea. Medical consultation is recommended for comprehensive management.
Being underweight can lead to nutritional deficiencies, weakened immune function, and osteoporosis. Focus on nutrient-dense foods and consult healthcare providers if unintentional weight loss occurs.
While BMI is useful for population-level assessments, it has significant individual limitations:
Professional Guidance: BMI is a screening tool, not a diagnostic instrument. Always consult with healthcare professionals for personalized health assessments and recommendations. Your overall health depends on many factors beyond BMI, including diet quality, physical activity, sleep, stress management, and genetic predispositions.
Type your weight (in kg or lbs) and height (in cm or inches). The calculator auto-converts to metric for the BMI formula.
BMI = weight in kg divided by height in meters squared. A 70 kg person who is 1.75 m tall has a BMI of 22.9.
Below 18.5 is underweight, 18.5-24.9 is normal, 25-29.9 is overweight, 30+ is obese. The calculator also shows the healthy BMI range for your height.
For related calculations, try our body fat calculator.
Formula: BMI = weight (kg) ÷ (height (m))². For imperial units: BMI = 703 × weight (lb) ÷ (height (in))². Morbid (Class III) obesity is BMI ≥ 40 (or BMI ≥ 35 with a related health condition).
BMI Category Range Example (5'9" adult) Underweight < 18.5 < 125 lb Normal weight 18.5 – 24.9 125 – 168 lb Overweight 25.0 – 29.9 169 – 203 lb Obese (I) 30.0 – 34.9 204 – 239 lb Obese (II) 35.0 – 39.9 240 – 267 lb Morbid (III) ≥ 40 ≥ 268 lb
Cross-checked against authoritative formulas (IRS, NIST, ACM) and updated for 2025/2026 tax years and rates.
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FAQ
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Morbid obesity (clinical name: Class III obesity) is defined as a BMI of 40 or higher, OR a BMI of 35+ with a serious weight-related health condition such as type 2 diabetes, hypertension, or sleep apnea. Enter your height and weight in the calculator above to see your BMI and which category you fall into.
How it works
Use BMI (with height and weight) to determine if you fall into the Class III (morbid) obesity range.
Type your height in feet/inches or centimeters above.
Type your current weight in pounds or kilograms.
The calculator shows your BMI instantly and places you into underweight, normal, overweight, obese class I, obese class II, or obese class III (morbid) categories.
If your BMI is ≥40, or ≥35 with a health condition, follow up with a primary care clinician or bariatric specialist to discuss treatment options tailored to your situation.
Understand BMI's limitations vs body fat percentage, especially for athletes and those at higher BMI ranges.
Holistic approach to health at higher BMI ranges using advanced calculators and clinical guidance.
Learn how BMI works, what its categories mean, and how to interpret results across the spectrum.