An adult who is 5 ft 9 in and weighs 165 lb has a BMI of 24.4, a healthy weight by CDC categories
Body mass index (BMI) is weight in kilograms divided by height in meters squared. At 5 ft 9 in (1.7526 m) and 165 lb (74.84 kg), that is 74.84 ÷ 1.7526² = 24.37, shown as 24.4. The CDC adult categories for people aged 20 and older put 24.4 in the healthy weight band, which runs from 18.5 to 24.9. The healthy weight range at this height is 125.0 to 168.9 lb. Under the lower BMI thresholds that NICE recommends for people with some family backgrounds (overweight from 23.0), the same result falls in the overweight band.
The result panel shows your BMI and category, the weight range for each category at your height, and how far your weight is from the healthy range. If you add a waist measurement it also shows the waist-to-height ratio. The sections below cover the method, the two sets of thresholds, a weight table by height, worked examples, the waist ratio, common mistakes and the limits of BMI.
How the calculator works
- Choose your units (lb, ft and in, or kg and cm) and enter height and weight. Switching units converts the numbers you have already typed.
- BMI is weight in kg ÷ height in m². The result is rounded half up to one decimal place.
- The category comes from that displayed number. A result shown as 25.0 is always overweight and 24.9 is always healthy weight, so the figure on screen and the category never disagree.
- The same rule is run backwards to find the weight range for every category at your height, in steps of 0.1 lb, and to show how far you are from the healthy range.
- If you enter a waist measurement, the calculator also divides it by your height and rates the ratio with the NICE bands.
Imperial entries are converted exactly, with 1 lb = 0.45359237 kg and 1 in = 2.54 cm, and then run through the same formula. Nothing you type is stored or sent to a server. The Copy link button puts the values after a # in the address, and the page reads and clears them on load.
Which BMI categories does the calculator use?
| BMI | CDC adult categories (20+) | NICE lower thresholds |
|---|---|---|
| Under 18.5 | Underweight | Underweight |
| 18.5 to 22.9 | Healthy weight | Healthy weight |
| 23.0 to 24.9 | Healthy weight | Overweight |
| 25.0 to 27.4 | Overweight | Overweight |
| 27.5 to 29.9 | Overweight | Obesity |
| 30.0 to 34.9 | Obesity class 1 | Obesity |
| 35.0 to 39.9 | Obesity class 2 | Obesity |
| 40.0 or more | Obesity class 3 | Obesity |
The CDC defines underweight as a BMI under 18.5, healthy weight as 18.5 to under 25, overweight as 25 to under 30 and obesity as 30 or above, with obesity split into class 1 (30 to under 35), class 2 (35 to under 40) and class 3 (40 or above). The WHO fact sheet uses the same two adult cut-offs: overweight is a BMI of 25 or more and obesity is 30 or more. This calculator uses the CDC categories as its main result.
NICE guideline NG246 says that people with a South Asian, Chinese, other Asian, Middle Eastern, Black African or African-Caribbean family background are prone to central adiposity and reach cardiometabolic risk at a lower BMI, so it recommends lower thresholds as a practical measure: overweight from 23 to 27.4 and obesity from 27.5. The calculator shows this as a second row under your main result. A BMI of 23.0 to 24.9 is therefore healthy weight by the CDC and overweight by the NICE thresholds, and neither source is wrong; they answer for different populations.
Weight bands by height (CDC categories)
| Height | Healthy weight (18.5 to 24.9) | Overweight (25.0 and above) | Obesity class 1 (30.0 and above) |
|---|---|---|---|
| 5 ft 0 in | 94.5 to 127.7 lb | from 127.8 lb | from 153.4 lb |
| 5 ft 2 in | 100.9 to 136.4 lb | from 136.5 lb | from 163.8 lb |
| 5 ft 4 in | 107.5 to 145.3 lb | from 145.4 lb | from 174.5 lb |
| 5 ft 6 in | 114.4 to 154.5 lb | from 154.6 lb | from 185.6 lb |
| 5 ft 8 in | 121.4 to 164.0 lb | from 164.1 lb | from 197.0 lb |
| 5 ft 10 in | 128.6 to 173.8 lb | from 173.9 lb | from 208.8 lb |
| 6 ft 0 in | 136.1 to 183.9 lb | from 184.0 lb | from 220.9 lb |
| 6 ft 2 in | 143.8 to 194.3 lb | from 194.4 lb | from 233.3 lb |
Each weight is the point where the BMI shown on screen enters that band, found in steps of 0.1 lb. At 5 ft 10 in, for example, 173.8 lb gives 24.94, which shows as 24.9 and is a healthy weight, while 173.9 lb gives 24.95, which shows as 25.0 and is overweight. For a height that is not in the table, enter it in the calculator; the table under the result gives every band for the height you typed.
Worked examples
| Height and weight | BMI | CDC category | NICE thresholds | Distance from healthy range |
|---|---|---|---|---|
| 5 ft 2 in · 95 lb | 17.4 | Underweight | Underweight | 5.9 lb below |
| 5 ft 4 in · 125 lb | 21.5 | Healthy weight | Healthy weight | Within range |
| 5 ft 9 in · 165 lb | 24.4 | Healthy weight | Overweight | Within range |
| 5 ft 6 in · 185 lb | 29.9 | Overweight | Obesity | 30.5 lb above |
| 5 ft 7 in · 200 lb | 31.3 | Obesity class 1 | Obesity | 40.7 lb above |
| 5 ft 5 in · 215 lb | 35.8 | Obesity class 2 | Obesity | 65.1 lb above |
The distance column is measured to the nearest edge of the healthy weight range for that height. It describes where a weight sits and is not a target. The 5 ft 9 in, 165 lb row is the example from the top of this page: a healthy weight by the CDC bands and overweight by the lower NICE thresholds. At 5 ft 6 in, 142.1 lb shows as 22.9 and 142.2 lb shows as 23.0, so the NICE overweight band starts at 142.2 lb, where the exact BMI of 22.95 rounds half up to 23.0.
Waist-to-height ratio
BMI says nothing about where fat is carried. NICE therefore also uses the waist-to-height ratio, which is your waist divided by your height, with the waist and height in the same unit. It rates the ratio as healthy central adiposity at 0.4 to 0.49, increased at 0.5 to 0.59 and high at 0.6 or more, and says these bands can be used for people with a BMI under 35, of both sexes and all ethnicities, including adults with high muscle mass. It also advises keeping your waist to less than half your height, a ratio under 0.5.
| Waist-to-height ratio | NICE rating | Waist at 5 ft 9 in (whole inches) |
|---|---|---|
| 0.40 to 0.49 | Healthy central adiposity | 28 to 34 in |
| 0.50 to 0.59 | Increased central adiposity | 35 to 41 in |
| 0.60 or more | High central adiposity | 42 in and above |
The calculator rounds the ratio to two decimal places and rates that number. A waist of 36 in at 5 ft 9 in gives a ratio of 0.52, which is increased central adiposity. The ratio is not rated when the BMI is 35 or more, because the NICE bands are meant for a BMI under 35.
Common mistakes
- Mixing units: dividing pounds by inches squared without a conversion factor gives a number far too small. Enter pounds with feet and inches, or kilograms with centimeters, and let the calculator convert.
- Reading a result against the wrong thresholds: a BMI of 24 is a healthy weight by the CDC bands and overweight by the lower NICE thresholds. Check which set of thresholds a report uses.
- Judging by the unrounded value: a calculator that rates the unrounded figure can show 25.0 and still say healthy weight. This one rates the number it displays, so 24.96 appears as 25.0 and is overweight.
- Applying adult categories to children: for ages 2 to 19 the CDC uses a BMI percentile for sex and age, and defines obesity as a BMI at or above the 95th percentile. The adult bands here are for people aged 20 and older.
- Treating BMI as a diagnosis: it is a screening measure. Use it with waist measurements and other health information.
Limits of BMI
- BMI does not distinguish between fat, muscle and bone mass, and it does not show where fat is located.
- NICE advises interpreting BMI with caution in adults with high muscle mass, because it may be a less accurate measure of central adiposity in this group.
- NICE also advises caution at 65 and over, taking into account other conditions and the possible protective effect of a slightly higher BMI when older.
- The categories and the waist ratio screen for risk. Decisions about diagnosis or treatment belong with a clinician who can look at blood pressure, blood sugar, lipids and your history. This calculator provides information and does not replace that assessment.
Date checked The BMI categories, the NICE thresholds and the waist-to-height bands on this page were checked against the CDC, WHO and NICE NG246 pages listed below on 2026-10-07. They will be rechecked if those sources change.
Sources
- 01CDC, Adult BMI CategoriesCategories for people 20 and older: underweight, healthy weight, overweight, obesity classes 1 to 3; ages 2 to 19 use percentiles
- 02CDC, About Body Mass Index (BMI)BMI does not distinguish fat, muscle and bone mass; obesity in children and teens at or above the 95th percentile
- 03WHO, Obesity and overweight (fact sheet)Adult overweight at BMI 25 or more and obesity at 30 or more
- 04NICE, NG246 Overweight and obesity management: Identifying and assessing overweight, obesity and central adiposityLower BMI thresholds of 23 and 27.5 for some family backgrounds; waist-to-height ratio bands 0.4, 0.5 and 0.6; caution at 65 and over and with high muscle mass
Frequently asked questions
How is BMI calculated?
Divide weight in kilograms by height in meters squared. For 5 ft 9 in and 165 lb that is 74.84 ÷ 1.7526² = 24.37, shown as 24.4. The calculator converts pounds and inches exactly (1 lb = 0.45359237 kg, 1 in = 2.54 cm).
What BMI is overweight or obese for an adult?
The CDC categories for people aged 20 and older are underweight under 18.5, healthy weight 18.5 to under 25, overweight 25 to under 30 and obesity 30 or above. Obesity is split into class 1 (30 to under 35), class 2 (35 to under 40) and class 3 (40 or above). The WHO uses the same cut-offs of 25 and 30.
Why does NICE use lower BMI thresholds for some people?
NICE says people with a South Asian, Chinese, other Asian, Middle Eastern, Black African or African-Caribbean background are prone to central adiposity and reach cardiometabolic risk at a lower BMI. It recommends overweight from 23 to 27.4 and obesity from 27.5. A BMI of 24 is a healthy weight by the CDC bands and overweight by these thresholds.
What is a healthy weight at 5 ft 9 in?
By the CDC bands the healthy weight range at 5 ft 9 in is 125.0 to 168.9 lb. Overweight starts at 169.0 lb and obesity class 1 at 202.9 lb.
Is a BMI of 24.96 healthy weight or overweight?
It is overweight. The calculator rounds to one decimal place and rates the number it shows, so 24.96 appears as 25.0, which is in the overweight band. Rating the unrounded value would show 25.0 next to a healthy weight label.
What waist-to-height ratio is healthy?
NICE rates 0.4 to 0.49 as healthy central adiposity, 0.5 to 0.59 as increased and 0.6 or more as high, for people with a BMI under 35. It advises keeping your waist to less than half your height. At 5 ft 9 in, a 34 in waist gives 0.49 and a 35 in waist gives 0.51.
Does muscle affect BMI?
Yes. BMI does not distinguish between fat, muscle and bone mass, so a very muscular person can have a BMI in the overweight range with little body fat. NICE advises interpreting BMI with caution in adults with high muscle mass, and the waist-to-height ratio can be used alongside it.
Can children and teens use this calculator?
No. The adult categories apply to people aged 20 and older. For ages 2 to 19 the CDC uses a BMI percentile for sex and age, and defines obesity as a BMI at or above the 95th percentile.