Enter your height and weight to calculate your Body Mass Index (BMI) and see where your result falls within the standard adult BMI categories.
Age does not change standard adult BMI formulas, but helps verify adult category eligibility.
Your BMI falls within the standard adult healthy-weight range.
Approximate body weight corresponding to key BMI targets based on your exact height:
| BMI | Classification | Weight |
|---|
Compare your previous weight against your current weight to evaluate change.
Calculate difference between an earlier BMI measurement and today.
BMI does not distinguish between skeletal muscle and body fat. Athletes and individuals with high muscle mass often register in the overweight or obesity categories despite possessing low body fat and exceptional cardiovascular health.
Standard adult BMI is not suitable for assessing gestational weight status. Pregnancy involves natural, vital weight gains attributable to maternal hydration, placenta, and fetal growth. Consult your prenatal healthcare provider for individualized care.
Derived from your locally stored calculation history.
Learn how Body Mass Index is calculated, what adult categories represent, and how to evaluate health beyond height and weight.
Body Mass Index is an internationally recognized biometric screening calculation that relates body weight to height.
Developed in the 19th century by Belgian mathematician Adolphe Quetelet, BMI provides an accessible, non-invasive method for evaluating weight categories across large populations.
BMI stands for Body Mass Index. It was originally termed the Quetelet Index of Obesity.
In 1972, physiologist Ancel Keys validated the index as the most practical proxy for body fat among relative weight ratios, popularizing the term Body Mass Index.
BMI represents the ratio of total mass to the square of stature.
By squaring height, the formula scales mass appropriately for two-dimensional to three-dimensional body volumetric proportions, producing a dimensionless index expressed in kg/m².
The standard metric formula is BMI = weight(kg) ÷ height(m)².
When working with imperial units, the formula requires a scaling conversion constant: BMI = (weight in pounds × 703) ÷ (height in inches)². The factor 703 converts pounds to kilograms and square inches to square meters.
Convert centimeters into meters, square that value, and divide kilograms by the result.
Example for 70 kg and 175 cm: 175 cm = 1.75 m. 1.75 × 1.75 = 3.0625. 70 ÷ 3.0625 = 22.86, rounding to 22.9.
Multiply pounds by 703 and divide by height in inches squared.
Example for 154 lb and 5 ft 9 in: 5 ft 9 in = 69 in. 69 × 69 = 4,761. 154 × 703 = 108,262. 108,262 ÷ 4,761 = 22.74, rounding to 22.7.
The World Health Organization establishes four primary adult categories.
Underweight (<18.5), Healthy Weight (18.5–24.9), Overweight (25.0–29.9), and Obesity (≥30.0). These thresholds apply to men and women aged 20 and older.
A BMI between 18.5 and 24.9 is statistically associated with the lowest incidence of lifestyle-related chronic diseases.
Cardiovascular conditions, type 2 diabetes, and hypertension show statistically minimal incidence within this range across large epidemiological cohorts.
A BMI below 18.5 indicates that an individual's body weight may be insufficient for their height.
Underweight status may be correlated with malnutrition, vitamin deficiencies, compromised immune response, or reduced bone mineral density.
A BMI between 25.0 and 29.9 signifies an elevated weight relative to height.
Being in the overweight category warrants assessing lifestyle factors such as dietary patterns, daily aerobic activity, and metabolic blood markers.
A BMI of 30.0 or higher is defined clinically as obesity.
Obesity is further stratified into Class 1 (30–34.9), Class 2 (35–39.9), and Class 3 (≥40). It is recognized as a complex, chronic condition requiring medical guidance.
Multiply the square of your height in meters by 18.5 and 24.9.
Lower Weight Bound = 18.5 × height(m)². Upper Weight Bound = 24.9 × height(m)². For a 1.80 m adult: 1.80² = 3.24. Healthy range = 59.9 kg to 80.7 kg.
Height is squared in the denominator, meaning small height inaccuracies substantially affect the resulting BMI.
An error of just 2.5 cm (1 inch) in height measurement can shift calculated BMI by almost a full point.
Weight has a linear 1:1 relationship with BMI at a constant height.
Gaining or losing 3 kilograms changes BMI by approximately 1.0 point for an individual of average height (175 cm).
While the mathematical formula is sex-neutral, physiological body fat distribution differs.
Women typically carry 10% to 12% essential fat compared to 2% to 5% in men, meaning that identical BMIs represent different fat fractions.
Adult cutoffs do not apply to individuals younger than 18 years.
Because body composition and proportions change dramatically during childhood and puberty, pediatric clinicians plot BMI on CDC growth charts to derive percentile rankings.
Standard BMI should not be used to monitor maternal weight status during gestation.
Healthy pregnancy involves substantial temporary weight increases attributable to the fetus, amniotic sac, placenta, and maternal vascular expansion.
Dense muscular development often causes athletes to score in the overweight or obese ranges.
Skeletal muscle is approximately 18% denser than adipose tissue. Athletes should rely on body composition analysis or waist-to-hip measurements.
BMI measures excess weight rather than excess adiposity.
A scale cannot distinguish whether a kilogram of weight consists of fat, muscle, skeletal mass, or intracellular hydration.
Body fat percentage provides a direct measurement of adipose mass relative to total weight.
Two individuals with identical 24.0 BMIs could have completely different body fat percentages (e.g. 12% vs. 28%) depending on physical fitness.
Waist circumference measures visceral intra-abdominal fat, which carries greater metabolic risk.
A waist circumference greater than 102 cm (40 in) for men or 88 cm (35 in) for women indicates elevated cardiometabolic risk regardless of BMI.
BMI is an indirect proxy that ignores fat distribution, bone density, ethnicity, and muscle mass.
Certain ethnic groups, including South Asian populations, exhibit higher risks for diabetes and cardiovascular disease at lower BMI thresholds (e.g. ≥23).
BMI accurately identifies excess body fat in roughly 80% of average sedentary adults.
Its accuracy diminishes substantially in elite athletes, highly active fitness enthusiasts, elderly individuals experiencing sarcopenia, and children.
Treat your BMI score as an informative screening indicator, not a definitive health diagnosis.
Combine your BMI result with lifestyle habits, cardiovascular fitness, balanced nutrition, blood lipid panels, and consultation with a healthcare professional.
Multiply weight in pounds by 703 and divide twice by height in inches.
Equation: BMI = (Weight_lb × 703) ÷ Height_in ÷ Height_in. This double division is computationally identical to dividing by height squared.
Divide weight in kg by height in meters, then divide by height in meters again.
Equation: BMI = Weight_kg ÷ Height_m ÷ Height_m. This avoids needing intermediate square calculations on a handheld calculator.
Both unit systems evaluate mathematically to the exact same dimensionless BMI score.
Whether measured as 70 kg / 1.75 m (22.86) or 154.3 lb / 68.9 in (22.86), the resulting Body Mass Index is mathematically equivalent.
Lowering BMI safely involves creating a moderate caloric deficit through balanced nutrition and regular physical activity.
Aim for gradual weight reduction of 0.5 to 1 kg (1 to 2 lb) per week to preserve lean muscle tissue and support metabolic health.
Gaining weight for underweight individuals should focus on nutrient-dense foods and resistance training.
Incorporate complex carbohydrates, healthy fats, quality proteins, and progressive overload resistance exercises to promote muscle hypertrophy over excess fat storage.
Exercise caution when evaluating athletes, older adults, pregnant individuals, and people with limb amputations or edema.
In these specific demographic subsets, relying exclusively on BMI without clinical context can lead to incorrect conclusions regarding health.
Direct answers regarding calculation formulas, accuracy, limitations, and healthy ranges.
Body Mass Index (BMI) is an anthropometric screening measure calculated from an individual's weight and height. It provides an estimate of body mass relative to stature and helps classify adults into standard health-screening categories: underweight, healthy weight, overweight, and obesity.
BMI is calculated by dividing body weight in kilograms by the square of height in meters: BMI = weight (kg) ÷ height² (m). In imperial units, the formula is BMI = (weight (lb) × 703) ÷ height² (in).
For adults aged 20 and older, the World Health Organization (WHO) and CDC classify a BMI between 18.5 and 24.9 as the standard healthy weight range.
A BMI below 18.5 is categorized as underweight for adults. If your BMI is under 18.5, consult a healthcare provider to explore potential underlying causes and nutritional requirements.
A BMI between 25.0 and 29.9 is categorized as overweight for adults according to standard clinical screening guidelines.
A BMI of 30.0 or higher is classified as obesity. It is typically sub-divided into Class 1 (30.0–34.9), Class 2 (35.0–39.9), and Class 3 (40.0 and above, sometimes called severe or morbid obesity).
The mathematical formula for calculating BMI is identical for adult men and adult women. However, because women naturally possess higher percentages of body fat than men at the same BMI, body composition may differ.
No. BMI measures total body mass relative to height, not body fat directly. It cannot distinguish between adipose tissue (fat), muscle mass, bone density, or extracellular fluid.
BMI is an accurate and reliable population-level screening metric. However, for individual health assessments, it is best used in combination with other measurements, such as waist circumference, body composition analysis, blood pressure, and metabolic laboratory panels.
BMI can misclassify muscular athletes as overweight or obese, and conversely may categorize older adults or sedentary individuals with low muscle mass as 'healthy weight' even if their visceral body fat percentage is elevated.
BMI is an indirect ratio of weight to squared height. Body fat percentage measures the actual proportion of fat mass to total body weight using methods like DEXA scans, bioelectrical impedance, or skinfold calipers.
Take your weight in kilograms and divide it by your height in meters squared. Example: 70 kg ÷ (1.75 m × 1.75 m) = 70 ÷ 3.0625 = 22.86 BMI.
Multiply your weight in pounds by 703, then divide by your height in inches squared. Example: 154 lb × 703 ÷ (69 in × 69 in) = 108,262 ÷ 4,761 = 22.74 BMI.
Convert centimeters to meters by dividing by 100 (e.g. 175 cm = 1.75 m). Then divide your weight in kilograms by meters squared.
Convert your height entirely into inches (feet × 12 + inches). For example, 5 ft 9 in = 5 × 12 + 9 = 69 inches. Then apply the imperial BMI formula: (weight in lb × 703) ÷ (height in inches)².
A healthy weight corresponds to a BMI between 18.5 and 24.9. For a height of 175 cm (5 ft 9 in), the healthy adult weight range is approximately 56.7 kg to 76.3 kg (125.0 lb to 168.3 lb).
Standard adult BMI categories (18.5–24.9) cannot be used for children or teens under age 18. Pediatric health evaluations use age- and sex-specific BMI percentiles based on growth charts.
No. Teenagers experience rapid growth spurts and hormonal changes that make adult BMI cutoffs inappropriate. Pediatric growth charts must be used instead.
Standard BMI should not be used to assess weight during pregnancy because maternal weight includes amniotic fluid, placenta, increased blood volume, and fetal growth. Consult an obstetric healthcare provider.
BMI has limited utility for strength athletes, bodybuilders, and rugby players because dense skeletal muscle weighs more per volume than fat, artificially inflating BMI into overweight or obesity ranges.
The standard adult formula remains constant across age groups, but body composition naturally changes as adults age, often resulting in loss of lean muscle mass and increased body fat.
The formula is the same for men and women. However, clinical interpretations often account for the biological reality that women have more essential body fat than men.
If you engage in regular resistance training, your muscle mass may be significantly higher than average, causing your BMI to register in the overweight or obesity range despite having low body fat.
A low BMI can result from genetics, high metabolism, inadequate caloric intake, chronic illness, or gastrointestinal absorption issues. Consult a physician for an individualized evaluation.
No. Weight is an essential variable in the BMI equation. Without weight, Body Mass Index cannot be computed.
No. Height is squared in the denominator of the equation. Both height and weight are mathematically mandatory.
No data is sent to or stored on our servers. Any calculations you choose to save remain strictly inside your web browser's local storage on your own device.
Yes. All computations execute 100% locally in your browser. You can even disconnect your internet connection and the calculator will continue working perfectly.
Yes. Once the page is loaded, all metric/imperial conversions, calculations, tables, and charts run completely offline.
Enter your height and weight above to calculate Body Mass Index instantly, review adult category ranges, and find your estimated healthy weight.
