BMI Calculator

What This Calculator Shows

This calculator is for the common question: "Given my height and weight, what is my BMI, and what does that number mean?" It works as a BMI calculator in pounds and inches, metric units, or mixed units, then converts everything to the standard Body Mass Index formula.

The result is most useful for adults age 20 and older. It shows:

• Your BMI: the height-adjusted weight number.
• Your category: underweight, healthy weight, overweight, or obesity using adult CDC ranges¹.
• Healthy weight range: the estimated adult weight range for your height.
• Distance to range: how far your current weight is from that range.
• BMI Prime and Ponderal Index: extra context for people who want more than the basic category.

Do not treat the result as a diagnosis. Treat it as a screening result that tells you whether the number is roughly where expected, worth tracking, or worth discussing with a healthcare provider.

Adult BMI Chart

Use this chart to read the result quickly. CDC adult BMI categories apply to adults age 20 and older¹.

Obesity is also commonly split into classes: Class 1 is 30 to less than 35, Class 2 is 35 to less than 40, and Class 3 is 40 or greater. The calculator uses these ranges for interpretation, but your personal risk still depends on more than the BMI number.

How The Number Is Calculated

BMI compares weight with height squared. CDC lists both the metric and US formulas²:

Metric: BMI = weight (kg) / height (m)^2
US:     BMI = weight (lb) / height (in)^2 * 703

Example:

Height = 5 ft 9 in = 69 in
Weight = 170 lb
BMI = 170 / 69^2 * 703 = 25.1

That result sits just inside the adult overweight range. The calculator rounds the display, so a hand calculation can differ slightly if you round height, weight, or decimals at a different step.

Your Healthy Weight Range

The healthy weight range is the most practical part of the result for many users. It answers the reverse question: "For this height, what weight would land in the adult healthy BMI range?"

Target weight (kg) = target BMI * height (m)^2
Target weight (lb) = target BMI * height (in)^2 / 703

Approximate adult healthy weight ranges:

This is what people often mean by a reverse BMI calculator. It is useful for orientation, but it should not become a rigid target. Waist circumference, body composition, strength, symptoms, medications, pregnancy status, and past weight history can all change what a reasonable goal looks like.

When BMI Needs More Context

BMI is simple because it uses only height and weight. That is also why it can mislead.

If you searched for a BMI calculator for men with muscle, the important point is that muscle can raise body weight without meaning the same body-fat level. CDC notes that BMI does not measure body fat directly and cannot separate fat from lean mass⁵.

The same applies to sex-specific searches such as online BMI calculator female. Adult BMI uses the same equation and category cutoffs, but interpretation can be different depending on body composition, waist size, pregnancy or postpartum status, menopause, health history, and lab results.

If you came here looking for an army BMI calculator, use this only as a general screening number. Army body composition standards are separate from the civilian adult BMI chart and include height-weight screening plus body fat assessment rules when required⁷.

Children And Teens

Children and teens need a different interpretation. CDC child and teen BMI tools use age, sex, height, and weight to calculate BMI-for-age percentiles for ages 2 through 19³. Percentiles matter because a healthy number changes as a child grows.

Use a child BMI calculator or pediatric growth chart for children and teenagers. For parents and caregivers, the goal is not to label a child from one number; it is to notice growth patterns early and get professional guidance when something looks concerning⁴.

What To Do With Your Result

The best next step depends on the pattern:

Higher body weight and obesity are associated with increased risk for conditions such as type 2 diabetes, heart disease, sleep apnea, and some cancers⁶. That does not mean BMI tells the whole story. It means the number is worth reading alongside the rest of your health picture.