BMI Calculator
Enter your height and weight to get your body mass index, a WHO or Asian-Pacific classification, a reference weight and your healthy weight range in one step.
Your numbers are calculated in your browser and never sent to a server
Enter your numbers
Metric: height in cm, weight in kg — or use the US units box
Pressing Enter works too
Your result
- Reference weight (BMI 22)
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- Weight vs. reference
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- Healthy weight range
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BMI cannot tell muscle from fat, so treat it as a screening guide, not a diagnosis. For a proper assessment, talk to a health professional.
How to use
Three steps
Enter your height and weight (use the US units box for feet, inches and pounds).
Pick the WHO or the Asian-Pacific standard. The same number can fall into a different category under each.
Your BMI, category, reference weight and healthy range appear together. No sign-up, nothing to install.
Good to know
How BMI is calculated, and what it can and cannot tell you
The BMI formula, with an example
Body mass index (BMI) compares your weight with your height. In metric units you divide your weight in kilograms by your height in meters, squared. In US units the same calculation uses a conversion factor of 703: multiply your weight in pounds by 703, then divide by your height in inches, squared. The calculator accepts either, and the US units box converts feet, inches and pounds to centimeters and kilograms for you. The formula was devised in the 1830s by the Belgian statistician Adolphe Quetelet to describe populations, not to diagnose individuals, and it is still used because it needs only a scale and a tape measure.
BMI = weight (kg) ÷ height (m)² | BMI = 703 × weight (lb) ÷ height (in)²
Example: a person who is 5 ft 9 in (69 inches) and weighs 160 lb has a BMI of 703 × 160 ÷ 69² = 112,480 ÷ 4,761, which is about 23.6, in the normal weight range.
WHO categories and the Asian-Pacific cut-offs
For adults, the World Health Organization and the U.S. Centers for Disease Control and Prevention use the same cut-offs: under 18.5 is underweight, 18.5 to 24.9 is normal weight, 25 to 29.9 is overweight, and 30 or above is obesity, divided into class 1 (30 to 34.9), class 2 (35 to 39.9) and class 3 (40 and over). Because people of Asian descent tend to carry more body fat and a higher risk of type 2 diabetes and heart disease at a lower BMI, the WHO also published Asia-Pacific cut-offs in 2000. Under those, 23 to 24.9 is considered overweight (at risk) and 25 or above is obesity. Countries including Korea, Japan and China use lower thresholds in their own guidelines. Use the toggle to see how the same number is classified under each standard.
Healthy weight range for your height
The healthy range is the weight at which your BMI falls between 18.5 and 24.9 (or 22.9 on the Asian-Pacific scale). It is wide on purpose, because bodies differ. The table below shows the WHO range for four common heights, rounded to whole pounds.
| Height | Healthy range (BMI 18.5–24.9) | Upper limit, Asian-Pacific (BMI 22.9) |
|---|---|---|
| 5 ft 0 in (152 cm) | 95–127 lb | 117 lb |
| 5 ft 6 in (168 cm) | 115–154 lb | 142 lb |
| 5 ft 10 in (178 cm) | 129–174 lb | 160 lb |
| 6 ft 2 in (188 cm) | 144–194 lb | 178 lb |
What the reference weight and the percentage mean
The calculator also shows a reference weight, the weight that would give you a BMI of 22 at your height. It sits near the middle of the healthy range and is a handy single target. The percentage next to it compares your weight with that reference: 100 percent means you are exactly at it, 110 percent means 10 percent above. It is a convenience figure, not a medical measure.
Limits of BMI
BMI cannot tell muscle from fat, so very muscular people can land in the overweight range with little body fat, while someone with low muscle mass can have a normal BMI and still carry excess fat. It does not show where fat is stored, and belly fat carries more health risk than fat elsewhere. It is not designed for children and teenagers, whose results must be read against age-and-sex growth charts (CDC percentiles), or for pregnant women. Older adults, athletes and people with certain medical conditions also need individual interpretation. The American Medical Association has acknowledged these limitations and encourages doctors to use BMI together with other measures such as waist circumference, body composition, blood pressure, blood sugar and family history.
Practical next steps
If your result is outside the healthy range, treat it as a prompt for a conversation, not a verdict. Measure your waist at the level of your belly button; a waist over about 40 inches for men or 35 inches for women is associated with higher risk in many guidelines, and lower thresholds apply for people of Asian descent. A clinician can interpret your numbers with your history in mind. To see how much energy your body uses each day, try the BMR Calculator, and to see what a workout burns, the Calories Burned Calculator.
Frequently asked questions
What is a healthy BMI?
For most adults, a BMI from 18.5 to 24.9 is classed as normal weight by the WHO and the CDC. On the Asian-Pacific scale the upper limit is 22.9. Staying inside the range is associated with lower risk of several conditions, but it is not a guarantee of health, and outside it is not a diagnosis.
Is the BMI calculator accurate for athletes or very muscular people?
BMI can overstate body fat in people with a lot of muscle, because muscle is dense and weighs more than fat per volume. If you train regularly, look at waist size, body-fat percentage and how you feel and perform, and use BMI only as a rough starting point.
Why do two BMI standards give me different results?
They use different cut-offs. The WHO standard marks overweight from 25, while the Asian-Pacific standard marks it from 23, because health risks rise at lower BMIs in many Asian populations. Choose the one recommended for your background and discuss it with your doctor.
How do I calculate BMI in pounds and inches?
Multiply your weight in pounds by 703 and divide by your height in inches squared. For example, 180 lb at 70 inches is 703 × 180 ÷ 4,900 = 25.8. You can also type feet, inches and pounds into the US units box and the calculator does the conversion for you.
Can I use BMI for my child?
Not with these adult categories. Children and teens are assessed with BMI-for-age percentiles, which compare a child with others of the same age and sex. Ask your pediatrician or use the CDC’s child and teen BMI tool.
Does BMI change with age?
The formula does not, but its meaning does. Older adults tend to lose muscle and height, and some research suggests a slightly higher BMI may be protective after about age 65. Interpretation for seniors is best left to a clinician.
Should I use BMI during pregnancy?
No. Weight gain during pregnancy is expected and the standard categories do not apply. Doctors track pregnancy weight against recommendations based on your pre-pregnancy BMI, so ask your prenatal care provider for the target range that fits you. After delivery, wait for your clinician’s guidance before using BMI to set weight goals, especially if you are breastfeeding.
Is my height and weight saved or uploaded?
No. The calculation runs in your browser and nothing is sent to a server or stored.
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