BMI Calculator
Calculate your Body Mass Index and see where you fall on the WHO weight classification scale.
What Is Body Mass Index (BMI)?
Contents
BMI Chart: Find Your BMI by Height and Weight
| Height | 120 lb | 140 lb | 160 lb | 180 lb | 200 lb | 220 lb | 250 lb | 280 lb |
|---|---|---|---|---|---|---|---|---|
| 5'0" | 23.4 | 27.3 | 31.2 | 35.2 | 39.1 | 43.0 | 48.8 | 54.7 |
| 5'2" | 21.9 | 25.6 | 29.3 | 32.9 | 36.6 | 40.3 | 45.7 | 51.2 |
| 5'4" | 20.6 | 24.0 | 27.5 | 30.9 | 34.3 | 37.8 | 42.9 | 48.1 |
| 5'6" | 19.4 | 22.6 | 25.8 | 29.1 | 32.3 | 35.5 | 40.4 | 45.2 |
| 5'8" | 18.2 | 21.3 | 24.3 | 27.4 | 30.4 | 33.5 | 38.0 | 42.6 |
| 5'10" | 17.2 | 20.1 | 23.0 | 25.8 | 28.7 | 31.6 | 35.9 | 40.2 |
| 6'0" | 16.3 | 19.0 | 21.7 | 24.4 | 27.1 | 29.8 | 33.9 | 38.0 |
| 6'2" | 15.4 | 18.0 | 20.5 | 23.1 | 25.7 | 28.2 | 32.1 | 35.9 |
| 6'4" | 14.6 | 17.0 | 19.5 | 21.9 | 24.3 | 26.8 | 30.4 | 34.1 |
Normal: 18.5–24.9 | Overweight: 25.0–29.9 | Obese: 30.0+ — Source: WHO Global Database on BMI
How BMI Is Calculated
The Formula
Metric: BMI = weight (kg) ÷ height (m)²
Imperial: BMI = 703 × weight (lbs) ÷ height (inches)²
Example: A person weighing 70 kg who is 1.75 m tall has a BMI of 70 ÷ (1.75)² = 22.9, which falls in the "Normal weight" category.
The factor of 703 in the imperial formula converts the result to match the metric calculation. Both formulas produce the same BMI value for the same person.
BMI Categories & Health Risks
| Category | BMI (kg/m²) | Associated Health Risk |
|---|---|---|
| Underweight | Below 18.5 | Nutritional deficiency, osteoporosis, immune impairment |
| Normal weight | 18.5 – 24.9 | Lowest overall risk of weight-related disease |
| Overweight | 25.0 – 29.9 | Increased risk of cardiovascular disease and type 2 diabetes |
| Obese Class I | 30.0 – 34.9 | High risk of metabolic syndrome and sleep apnea |
| Obese Class II | 35.0 – 39.9 | Very high risk; medical intervention often recommended |
| Obese Class III | 40.0 and above | Extremely high risk; associated with reduced life expectancy |
Limitations of BMI
- Muscle mass: Athletes and muscular individuals may have a high BMI despite low body fat. A 2012 study found that BMI misclassified 48% of women and 25% of men when compared to body fat percentage measurements.
- Age: Older adults tend to have more body fat than younger adults at the same BMI. The relationship between BMI and mortality shifts upward with age.
- Sex: Women generally carry more body fat than men at equivalent BMI values.
- Ethnicity: Asian populations may face elevated health risks at lower BMI thresholds (23+), while some Pacific Islander populations may have lower risk at higher BMI values.
- Fat distribution: Central (abdominal) obesity carries higher cardiovascular risk than peripheral fat. Waist circumference and waist-to-hip ratio can supplement BMI for a more complete picture.
Frequently Asked Questions
What is BMI?
Body Mass Index (BMI) is a numerical value calculated from your weight and height. It is used as a screening tool to categorize individuals into weight categories: underweight (below 18.5), normal weight (18.5–24.9), overweight (25–29.9), and obese (30 and above). The formula was adopted by the WHO in the 1990s as a standard health metric.
How is BMI calculated?
BMI is calculated by dividing your weight in kilograms by your height in meters squared: BMI = weight (kg) / height (m). For imperial units, the formula is: BMI = 703 × weight (lbs) / height (inches). Both formulas produce the same result.
Is BMI accurate for everyone?
No. BMI does not directly measure body fat and may misclassify muscular individuals as overweight or obese. It also does not account for age, sex, ethnicity, or body fat distribution. A 2016 study in the International Journal of Obesity found that over 54 million Americans classified as "overweight" or "obese" by BMI were actually metabolically healthy. BMI is best used as an initial screening tool alongside other measurements like waist circumference and body fat percentage.
What is a healthy BMI range?
According to the World Health Organization, a BMI between 18.5 and 24.9 is considered normal weight. However, optimal BMI may vary. Some large meta-analyses suggest that a BMI of 22–25 is associated with the lowest all-cause mortality risk. For older adults (65+), slightly higher BMI values (23–27) may be associated with better outcomes, a phenomenon sometimes called the "obesity paradox."
Does BMI differ by age or sex?
The standard BMI formula and categories are the same for adult men and women. However, women naturally carry a higher percentage of body fat than men at the same BMI. For children and teens (ages 2–19), BMI is interpreted using age- and sex-specific percentile charts from the CDC rather than fixed cutoffs. This calculator is designed for adults aged 18 and older.
Should I use BMI or body fat percentage?
Both metrics provide useful but different information. BMI is simpler to calculate and widely used in clinical settings. Body fat percentage is more precise but requires specialized equipment (DEXA scan, calipers, or bioelectrical impedance). For most people, BMI serves as a reasonable first approximation. If you exercise regularly or have an unusual body composition, body fat percentage may be more informative.
Sources & Methodology
- World Health Organization. Obesity: preventing and managing the global epidemic. WHO Technical Report Series 894. 2000.
- Keys A, Fidanza F, Karvonen MJ, Kimura N, Taylor HL. Indices of relative weight and obesity. J Chronic Dis. 1972;25(6-7):329-343.
- Flegal KM, Kit BK, Orpana H, Graubard BI. Association of all-cause mortality with overweight and obesity using standard body mass index categories: a systematic review and meta-analysis. JAMA. 2013;309(1):71-82.
- Nuttall FQ. Body Mass Index: Obesity, BMI, and Health: A Critical Review. Nutr Today. 2015;50(3):117-128.
- National Heart, Lung, and Blood Institute. Clinical Guidelines on the Identification, Evaluation, and Treatment of Overweight and Obesity in Adults. NIH Publication No. 98-4083. 1998.
This calculator uses peer-reviewed formulas and clinical guidelines. Results are estimates and should not replace professional medical advice.
Medical Disclaimer: This tool provides general educational estimates. Always consult your prescribing physician or healthcare provider before making medication changes or interpreting results from population-based models.