How to read the adult BMI chart
Reading the chart takes three steps: find your BMI number, scan the range column until the number falls inside a row, and read the category label for that row. A BMI of 22.4, for example, falls between 18.5 and 24.9, so it lands in the healthy weight row. A BMI of 31 sits between 30.0 and 34.9, which falls in the obesity Class 1 row.
One detail matters more than most people expect: the chart reports BMI as a single decimal number, not as a whole number. The boundaries are written at one decimal place, so 24.9 and 25.0 are different rows. Rounding a value such as 24.96 up to 25.0 can move it into the next category, and the chart itself provides no rule for rounding. Use the value your measurement produced, and if you are comparing against a boundary, treat the difference as a cue to look at the broader picture rather than as a firm verdict.
The chart is a reference table, not a diagnosis. It tells you which range a number falls into; it does not tell you why that number is what it is or what it means for your individual health.
- Locate the numeric BMI value you want to classify.
- Scan the range column for the row that contains that value.
- Read the category label in the same row.
- Keep the decimal place you measured — do not round across a boundary without noting it.
Adult BMI category ranges table
This table reproduces the adult BMI category ranges and labels used by the Centers for Disease Control and Prevention, the US national public health agency. Obesity is listed as one category and then subdivided into three classes, so the table below shows both the broad category and the class boundaries in one place.
- Underweight: below 18.5
- Healthy Weight: 18.5 to 24.9
- Overweight: 25.0 to 29.9
- Obesity: 30.0 or greater
- Obesity Class 1: 30.0 to 34.9
- Obesity Class 2: 35.0 to 39.9
- Obesity Class 3 (Severe Obesity): 40.0 or greater
| BMI range | Category | Subdivision |
|---|---|---|
| Below 18.5 | Underweight | — |
| 18.5 to 24.9 | Healthy Weight | — |
| 25.0 to 29.9 | Overweight | — |
| 30.0 or greater | Obesity | Class 1: 30.0 to 34.9 |
| 30.0 or greater | Obesity | Class 2: 35.0 to 39.9 |
| 30.0 or greater | Obesity | Class 3: 40.0 or greater |
Boundary values between categories
The boundaries are the numbers where one row ends and the next begins: 18.5, 25.0, 30.0, 35.0 and 40.0. In the published table, the healthy weight row is written as 18.5 to 24.9 and the overweight row as 25.0 to 29.9. That wording leaves no gap between 24.9 and 25.0 at the precision shown, but it also does not state in words how a value exactly equal to 18.5 is assigned.
Because of that, a BMI that lands exactly on a printed boundary should be treated with care. The chart supports saying which rows the boundary numbers separate; it does not support declaring that a boundary value belongs to one specific category. If your number sits exactly on 18.5, 25.0, 30.0, 35.0 or 40.0, note the adjacent categories rather than forcing a single label, and discuss the result with a healthcare provider if you want a clinical interpretation.
A related point is precision. A BMI carried to three or more decimal places is not more meaningful than one carried to one decimal place, because height and weight measurements themselves carry rounding. Comparing 24.98 and 25.01 against the chart treats two nearly identical numbers as different categories.
- Printed boundary numbers: 18.5, 25.0, 30.0, 35.0 and 40.0.
- Adjacent rows: 18.5 separates underweight from healthy weight; 25.0 separates healthy weight from overweight; 30.0 separates overweight from obesity; 35.0 and 40.0 separate the obesity classes.
- A value exactly on a boundary is best read as sitting between two rows rather than as a settled classification.
- Carry your measured value at the same precision the chart uses rather than adding decimal places.
What each category label means in plain language
The labels describe ranges, and it is worth separating what they do say from what they do not. Underweight means the number falls below 18.5. Healthy Weight means it falls between 18.5 and 24.9. Overweight means 25.0 to 29.9. Obesity means 30.0 or greater, with Class 1 at 30.0 to 34.9, Class 2 at 35.0 to 39.9, and Class 3, also labeled severe obesity in the published table, at 40.0 or greater.
The label Healthy Weight is a range name, not a guarantee of health, and the label Overweight or Obesity is a range name, not a diagnosis. The CDC describes BMI as a screening measure that is not intended to diagnose disease or illness. A screening measure sorts people into groups so that further conversation can happen; it does not identify what is happening in an individual body.
The CDC also notes that BMI is one potential health indicator to be considered alongside other factors when assessing an individual's health, and that results should be discussed with a healthcare provider. In practice that means the chart is most useful as a starting point for a conversation rather than as an endpoint. Two people in the same row can have very different health circumstances, and the chart gives you no way to tell them apart.
- Underweight: below 18.5 — the range below the healthy weight band.
- Healthy Weight: 18.5 to 24.9 — the range label applied to the middle band.
- Overweight: 25.0 to 29.9 — the range above healthy weight and below obesity.
- Obesity: 30.0 or greater — subdivided into Class 1, Class 2 and Class 3.
- None of these labels is a diagnosis, and none of them explains why a person's BMI falls where it does.
Why the chart is for adults only
The adult BMI chart is built for people 20 and older. The CDC states plainly that its BMI calculator is for adults 20 and older, and it directs children and teens from 2 through 19 years to a separate BMI Calculator for Children and Teens.
The reason for the split is that growing bodies change shape and composition as they develop, so a single fixed set of numeric cutoffs does not describe them the way it describes adults. Children and teens are assessed with age- and sex-specific growth references rather than the adult ranges in this table, and the category names and boundaries used for them are not the same as the ones shown here.
The practical consequence is simple: if you are checking a number for someone under 20, this chart is the wrong reference. Use the pediatric growth-based tool instead, or ask a healthcare provider to interpret the measurement.
- This chart and the CDC adult calculator cover ages 20 and older.
- Children and teens ages 2 through 19 are assessed with a separate calculator based on growth references, not the adult ranges.
- Do not apply the adult category labels to a child or teen's BMI number.
Common misreadings of the chart
Several recurring errors make the chart seem to say more than it does. The most frequent is treating a category label as a diagnosis. The CDC describes BMI as a screening measure that is not intended to diagnose disease or illness, and it states that the calculator is not a substitute for professional medical advice. A row in a table cannot tell you whether you have a medical condition.
A second misreading is assuming the chart supplies a goal. The rows describe where a number falls; they are not targets, and the chart contains no guidance about changing your number. A third is treating a one-decimal difference as meaningful: moving from 24.9 to 25.0 crosses a printed boundary but does not represent a meaningful change in a person's body.
A fourth is forgetting what BMI leaves out. BMI is calculated from height and weight alone, so it does not distinguish muscle from fat, does not describe where fat is stored, and does not capture fitness, diet, sleep, smoking, family history or other factors a clinician would weigh. Two people can share a category and have very different health profiles. A fifth is applying adult ranges to children and teens, which the age guidance above rules out.
- A category label is not a diagnosis.
- A range is not a personal goal or a treatment plan.
- Small moves across a boundary rarely reflect a meaningful physical change.
- BMI does not separate muscle from fat or describe fat distribution.
- Adult ranges do not apply to anyone under 20.
- A single reading is one data point, not a full health assessment.
Using the chart alongside your own numbers
If you want to use the chart on your own measurements, note your height and weight, compute BMI as weight in kilograms divided by height in meters squared, or as 703 times weight in pounds divided by height in inches squared, and keep the result at one decimal place before matching it to a row. Writing the units next to each measurement and the date next to the result helps you compare readings fairly later, since a number without units or a date is hard to interpret.
If you prefer not to calculate by hand, the CDC provides an adult BMI calculator that performs the same computation and presents the same categories. Either route produces a number that the table above can classify.
Whichever method you use, the chart is the last step, not the first. Measure, calculate, classify, and then decide what question you actually want answered. If the answer you want is about your health rather than about a range, the CDC's guidance is to discuss it with a healthcare provider, who can consider the factors the chart omits.
- Record height and weight with units, plus the date.
- Calculate BMI and keep one decimal place.
- Match the result to the range column in the table.
- Compare readings taken the same way over time rather than mixing methods.
- Take questions about personal health to a healthcare provider.
Frequently asked questions
Is the same BMI chart used for adult men and women?
Yes. The adult BMI category ranges published by the CDC are a single set of numbers, and the table applies the same cutoffs regardless of sex. The chart itself does not contain separate male and female columns. That does not mean the number captures everything: BMI is calculated from height and weight alone and does not account for differences in body composition between individuals, which is one reason the CDC describes it as a screening measure to be considered with other factors rather than as a standalone assessment.
Sources: Centers for Disease Control and Prevention (CDC)Can a BMI exactly on a boundary value count as two categories?
The published table does not state how a value exactly equal to a boundary is assigned. It writes the healthy weight row as 18.5 to 24.9 and the overweight row as 25.0 to 29.9, so the rows are separated at the printed boundaries, but the wording does not resolve which category a value of exactly 25.0 belongs to. The honest reading is that a value sitting precisely on 18.5, 25.0, 30.0, 35.0 or 40.0 is at the division between two rows. If you need a definite classification for a boundary value, ask a healthcare provider rather than treating the table as a tie-breaker.
Sources: Centers for Disease Control and Prevention (CDC)Why does the chart not include children or teens?
Because the adult category ranges are defined for adults 20 and older. The CDC states that its BMI calculator is for adults 20 and older and directs children and teens ages 2 through 19 to a separate BMI Calculator for Children and Teens. Children and teens are assessed against growth references that account for age and sex rather than the fixed numeric cutoffs in the adult table, so applying these adult rows to a younger person would misclassify the result.
Sources: Centers for Disease Control and Prevention (CDC)Does a category label mean I have a medical condition?
No. A category label identifies which numeric range a BMI falls into; it is not a diagnosis. The CDC states that BMI is a screening measure and is not intended to diagnose disease or illness, and that its calculator is not a substitute for professional medical advice. The CDC also notes that BMI should be discussed with a healthcare provider because it is one potential health indicator among others to be considered when assessing an individual's health. If you have questions about your own health, a healthcare provider can interpret the number in context.
Sources: Centers for Disease Control and Prevention (CDC)Should I use the broad obesity category or the class subdivision?
The CDC table presents obesity as a single category at 30.0 or greater and then subdivides it into Class 1 at 30.0 to 34.9, Class 2 at 35.0 to 39.9, and Class 3, labeled severe obesity, at 40.0 or greater. The broad label is the category; the classes are finer subdivisions within it. Which level of detail matters depends on what you are doing — a quick personal check may only need the broad category, while a clinical conversation may refer to the class. Neither level is a diagnosis on its own.
Sources: Centers for Disease Control and Prevention (CDC)How precise should my BMI number be when I compare it to the chart?
Use the same one-decimal precision the chart uses. The printed boundaries are written to one decimal place, and a BMI carried to three or more decimals implies a level of precision that height and weight measurements generally do not have. Keeping one decimal place also keeps the comparison honest: 24.9 and 25.0 fall in different rows by the chart's own wording, and that is a division the table draws rather than a meaningful difference in a person's body.
Sources: Centers for Disease Control and Prevention (CDC)Does the chart tell me what my BMI should be?
No. The chart is a reference for classifying a number, not a target or a treatment plan. It shows where the range boundaries sit and which label applies to each range. The CDC frames BMI as a screening measure to be discussed with a healthcare provider and considered alongside other health factors, and it notes that its calculator is not a substitute for professional medical advice. If you want to understand what a specific reading means for you, that conversation belongs with a healthcare provider rather than with the table.
Sources: Centers for Disease Control and Prevention (CDC)Sources
- Adult BMI Calculator — Centers for Disease Control and Prevention (CDC)