C
CalcSpeed

BMI Calculator

Calculate your Body Mass Index using US or metric units and see where you fall.

AD SLOT 1 — Above Calculator

Your Measurements

ft
in

Enter your height in feet and inches. Your height is used to calculate Body Mass Index.

lbs

Your body weight in pounds without shoes or heavy clothing.

Your BMI

23.6
Normal Weight
Normal range: 18.5 – 24.9
10 18.5 25 30 35 40+
Underweight Below 18.5
Normal Weight 18.5 – 24.9
Overweight 25.0 – 29.9
Obese 30.0+
AD SLOT 2 — Below Calculator / Above FAQ

Frequently Asked Questions

What is BMI and what does it measure?
Body Mass Index (BMI) is a numerical value derived from your height and weight. It's calculated as weight in kilograms divided by the square of height in meters (kg/m²). BMI is a widely used screening tool to identify weight categories—underweight, normal weight, overweight, and obese—that may be associated with various health risks. However, BMI does not directly measure body fat or account for muscle mass, age, sex, or ethnicity.
What are the BMI categories for adults?
The standard adult BMI categories as defined by the CDC and WHO are: Underweight (BMI below 18.5), Normal weight (18.5–24.9), Overweight (25.0–29.9), and Obese (30.0 and above). Obesity is further subdivided into Class 1 (30–34.9), Class 2 (35–39.9), and Class 3/Severely Obese (40 and above). These thresholds are the same for both men and women.
Is BMI an accurate measure of health?
BMI is a useful population-level screening tool but has limitations when applied to individuals. It does not distinguish between fat and muscle mass, so highly muscular athletes may be classified as overweight despite having very low body fat. It also doesn't account for where fat is distributed on the body (visceral fat around the abdomen is more dangerous than subcutaneous fat). BMI should be considered alongside other health metrics like waist circumference, blood pressure, cholesterol, and blood glucose levels.
What is a healthy BMI for women?
The CDC uses the same BMI categories for adult men and women: a BMI of 18.5 to 24.9 is considered normal weight. However, research suggests women generally have more body fat than men at the same BMI due to physiological differences. Some health professionals use adjusted body fat percentage targets rather than BMI alone to assess health risk in women. Age also affects what's optimal—older adults may have different risk profiles at the same BMI.
What is a healthy BMI for men?
For adult men, the normal BMI range is 18.5 to 24.9, the same as for women. Men typically carry less body fat at the same BMI compared to women. That said, BMI still serves as a valid screening indicator for most men. Studies consistently show that men with a BMI over 30 face significantly elevated risks of type 2 diabetes, heart disease, and sleep apnea, making weight management an important health consideration.
How is BMI different for children?
For children and teens (ages 2–19), BMI is interpreted differently using age- and sex-specific percentile charts rather than fixed cutoff numbers. The categories are: Underweight (below 5th percentile), Healthy weight (5th–84th percentile), Overweight (85th–94th percentile), and Obese (95th percentile or above). This is because children's bodies are still developing and normal BMI values change with age. Always consult a pediatrician for children's weight assessment.
What health risks are associated with high BMI?
A high BMI (overweight or obese categories) is associated with increased risk of type 2 diabetes, heart disease, high blood pressure, stroke, sleep apnea, certain cancers (including breast, colon, and kidney), osteoarthritis, and fatty liver disease. The risk increases with BMI level and is compounded by other factors like physical inactivity, smoking, and poor diet. Even a modest 5–10% reduction in body weight can meaningfully reduce many of these risks.
What should I do if my BMI is outside the normal range?
If your BMI is outside the 18.5–24.9 normal range, the best first step is to consult with your healthcare provider. They can put your BMI in context with other health indicators and your personal medical history. For those in the overweight or obese range, sustainable lifestyle changes—regular physical activity, reduced calorie intake, improved sleep, and stress management—are typically recommended. Avoid crash diets; slow and steady weight loss of 1–2 pounds per week is most maintainable long-term.

What Your BMI Number Actually Means

BMI was created in the 1830s by a Belgian mathematician named Adolphe Quetelet. He was doing population studies — not clinical health assessments. That context matters when you're interpreting your own number, because the formula was never designed to evaluate individual health.

The math itself is straightforward: weight in kilograms divided by height in meters squared. A 5'9" person weighing 180 pounds gets a BMI of 26.6, which lands in the overweight category. That same number describes both a person carrying excess body fat and a college athlete with significant muscle mass. BMI cannot tell the difference between the two.

This is the measurement's core limitation. It has no way to distinguish fat from muscle. For most people who aren't athletes, BMI correlates reasonably well with health risk — research consistently shows that BMIs above 30 are associated with higher rates of type 2 diabetes, heart disease, and sleep apnea. But the association is statistical, not individual. Two people with identical BMIs can have very different health profiles.

Doctors use BMI alongside waist circumference, blood pressure, cholesterol, and blood glucose — not as a standalone verdict. A waist measurement above 40 inches for men or 35 inches for women signals higher cardiovascular risk regardless of BMI. If your BMI is outside the normal range, the most useful next step is a conversation with your doctor, not a dramatic diet change.

Children and teens use entirely different BMI charts based on age and sex percentiles, because healthy BMI ranges change as kids grow. The adult categories above do not apply to anyone under 18.

AD SLOT 3 — Below FAQ

About This BMI Calculator

This BMI calculator uses the standard formula approved by the CDC and the World Health Organization. For US units, it converts your height in feet and inches plus weight in pounds to metric equivalents before computing BMI. For metric input, it uses height in centimeters and weight in kilograms directly. The formula is: BMI = weight(kg) / height(m)².

The visual gauge maps your BMI onto the five standard ranges—underweight, normal, overweight, obese class I, and obese class II+—so you can see at a glance where your number falls. Remember that BMI is a screening tool, not a diagnosis. If you have concerns about your weight or health, always consult a qualified healthcare professional.