BMI Calculator
Body mass index is your weight in kilograms divided by your height in meters squared. At 180 cm and 75 kg that is 75 ÷ 1.8², about 23.1, in the healthy range (see it worked out). The calculator also shows the healthy weight for your height.
Calculate your BMI
For adults 20 and older. The result updates as you type.
Check your input
- Healthy weight for your height
- 0
- To reach the healthy range
- 0
- BMI Prime
- 0
Where your BMI sits
WHO adult categories, kg/m²How to Use This Calculator
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Pick your units
Choose metric (cm, kg), US (feet, inches, pounds) or UK (feet, inches, stones). Values you already typed are converted when you switch.
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Enter height and weight
Your BMI appears as you type, with its category. If one of the listed backgrounds applies to you, switch the cut-offs to the lower thresholds.
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Read the healthy range
See the weight range that is healthy for your height, how far you are from it, and where your BMI sits on the scale.
How to calculate BMI
Body mass index, or BMI, compares your weight with your height. It is a quick screening number that doctors and public health agencies use to sort adults into weight categories. You only need two measurements and one division.
In metric units, square your height in meters and divide your weight by the result. At 180 cm and 75 kg, 1.8 × 1.8 = 3.24, and 75 ÷ 3.24 is about 23.1. In pounds and inches, multiply the weight by 703 first. At 5 feet 9 inches, which is 69 inches, and 160 pounds: 703 × 160 = 112,480, 69 × 69 = 4,761, and 112,480 ÷ 4,761 is about 23.6. BMI is usually given to one decimal place.
BMI categories for adults
For adults aged 20 and over, the same categories apply to men and women of every age. The WHO and the CDC use the standard thresholds. NICE, which sets clinical guidance in England, uses lower thresholds for people of some ethnic backgrounds, explained further down this page.
| Category | Standard | Lower thresholds |
|---|---|---|
| Underweight | under 18.5 | under 18.5 |
| Healthy weight | 18.5 to 24.9 | 18.5 to 22.9 |
| Overweight | 25 to 29.9 | 23 to 27.4 |
| Obesity class 1 | 30 to 34.9 | 27.5 to 32.4 |
| Obesity class 2 | 35 to 39.9 | 32.5 to 37.4 |
| Obesity class 3 | 40 or more | 37.5 or more |
The CDC defines the bands with "less than": a healthy weight is a BMI of 18.5 to less than 25. The calculator therefore places you by your unrounded BMI. It shows one decimal, or two when rounding to one would land on the other side of a band edge, so a BMI of 24.996 shows as 24.99 and counts as a healthy weight. Tables like the one above write the same band as 18.5 to 24.9.
Healthy weight for your height
Turning the formula around tells you which weights give a healthy BMI at a given height: multiply 18.5 and 25 by your height in meters squared. At 180 cm the healthy range runs from 18.5 × 3.24, about 60 kg, to just under 25 × 3.24 = 81 kg. The table gives the range for common heights with the standard thresholds, rounded so that every weight listed is inside the range.
| Height | cm | Pounds | Kilograms |
|---|---|---|---|
| 4 ft 10 in | 147 | 89 to 119 | 40.2 to 54.2 |
| 5 ft 0 in | 152 | 95 to 128 | 43.0 to 58.0 |
| 5 ft 2 in | 157 | 102 to 136 | 45.9 to 61.9 |
| 5 ft 4 in | 163 | 108 to 145 | 48.9 to 66.0 |
| 5 ft 6 in | 168 | 115 to 154 | 52.0 to 70.2 |
| 5 ft 8 in | 173 | 122 to 164 | 55.2 to 74.5 |
| 5 ft 10 in | 178 | 129 to 174 | 58.5 to 79.0 |
| 6 ft 0 in | 183 | 137 to 184 | 61.9 to 83.6 |
| 6 ft 2 in | 188 | 145 to 194 | 65.4 to 88.3 |
| 6 ft 4 in | 193 | 152 to 205 | 69.0 to 93.1 |
BMI chart
Find your height on the left and your weight along the top. The shaded cells are in the healthy range (18.5 to under 25). Values are rounded to one decimal.
Swipe the chart sideways to see heavier weights.
| Height | 100 lb | 120 lb | 140 lb | 160 lb | 180 lb | 200 lb | 220 lb | 240 lb | 260 lb |
|---|---|---|---|---|---|---|---|---|---|
| 5′0″ | 19.5 | 23.4 | 27.3 | 31.2 | 35.2 | 39.1 | 43.0 | 46.9 | 50.8 |
| 5′2″ | 18.3 | 21.9 | 25.6 | 29.3 | 32.9 | 36.6 | 40.2 | 43.9 | 47.6 |
| 5′4″ | 17.2 | 20.6 | 24.0 | 27.5 | 30.9 | 34.3 | 37.8 | 41.2 | 44.6 |
| 5′6″ | 16.1 | 19.4 | 22.6 | 25.8 | 29.1 | 32.3 | 35.5 | 38.7 | 42.0 |
| 5′8″ | 15.2 | 18.2 | 21.3 | 24.3 | 27.4 | 30.4 | 33.5 | 36.5 | 39.5 |
| 5′10″ | 14.3 | 17.2 | 20.1 | 23.0 | 25.8 | 28.7 | 31.6 | 34.4 | 37.3 |
| 6′0″ | 13.6 | 16.3 | 19.0 | 21.7 | 24.4 | 27.1 | 29.8 | 32.5 | 35.3 |
| 6′2″ | 12.8 | 15.4 | 18.0 | 20.5 | 23.1 | 25.7 | 28.2 | 30.8 | 33.4 |
| 6′4″ | 12.2 | 14.6 | 17.0 | 19.5 | 21.9 | 24.3 | 26.8 | 29.2 | 31.6 |
Lower BMI thresholds for some backgrounds
The link between BMI and health risk is not the same for everyone. People with a South Asian, Chinese, other Asian, Middle Eastern, Black African or African-Caribbean background are more likely to store fat around the waist, and their risk of type 2 diabetes and heart disease rises at a lower BMI. NICE guidance (NG246) therefore counts overweight from a BMI of 23 and obesity from 27.5 for these groups, and lowers the thresholds for obesity classes 2 and 3 by 2.5 as well.
A WHO expert consultation reached a similar view for Asian populations in 2004. It kept the standard cut-offs for international use and proposed extra action points at 23, 27.5, 32.5 and 37.5. In the calculator, choose "Lower thresholds" under Cut-offs to use these values. Your BMI stays the same; only the category and the healthy range change.
Show 170 cm and 70 kg with the lower thresholds
What BMI does not tell you
BMI only knows your height and weight. As the CDC puts it, BMI does not distinguish between fat, muscle and bone, and it does not show where in the body fat is stored. A rugby player and an inactive person of the same height and weight get the same number.
Fat around the waist carries more risk than fat elsewhere, so a waist measurement is a useful second check. The NHLBI in the United States says a waist of more than 35 inches for women or more than 40 inches for men increases the risk of heart disease and type 2 diabetes. NICE in the UK uses the waist-to-height ratio: divide your waist by your height in the same units. A ratio from 0.4 to 0.49 is healthy, 0.5 to 0.59 means increased risk, and 0.6 or more means higher risk still. NICE notes that this ratio also works for people with a lot of muscle.
BMI is a screening tool, so treat your result as a reason to look further. If yours is outside the healthy range, or you are worried about your weight, a doctor can look at the whole picture, including blood pressure, blood tests and family history.
BMI for children and teens
This calculator is for adults. Children and teens aged 2 to 19 are still growing, and their body fat changes with age and differs between boys and girls. Their BMI is compared with other children of the same age and sex and given as a percentile. Under the CDC charts, below the 5th percentile is underweight, the 5th to under the 85th is a healthy weight, the 85th to under the 95th is overweight, and the 95th percentile or above is obesity. Use the CDC child and teen BMI calculator for anyone under 20.
BMI Prime
BMI Prime is your BMI divided by 25, the upper limit of the standard healthy range. A result under 1 means you are below that limit; 1.2 means your BMI is 20% above it. Some people find it easier to read than the raw number. It is tied to the standard limit of 25, so the calculator hides it when you choose the lower thresholds.
Sources
- CDC, About body mass index, including what BMI does not measure.
- CDC, Child and teen BMI categories.
- CDC, Adult BMI categories.
- WHO, Obesity and overweight fact sheet.
- NICE, Overweight and obesity management (NG246), published January 2025.
- WHO Expert Consultation, Appropriate body-mass index for Asian populations, The Lancet, 2004.
- NHLBI, Assessing your weight and health risk.
Frequently Asked Questions
What is a healthy BMI for adults?
For adults 20 and older, a BMI from 18.5 to under 25 (often written 18.5 to 24.9) is in the healthy weight range. Below 18.5 is underweight, 25 to 29.9 is overweight, and 30 or more is obesity. These are the categories used by the WHO and the CDC.
Is BMI different for men and women?
No. For adults the same BMI categories apply to men and women and to all ages. The CDC states that adult categories are based on BMI regardless of age or sex. BMI is a screening measure, so a doctor will look at more than this one number.
How do I calculate BMI with pounds and inches?
Multiply your weight in pounds by 703, then divide by your height in inches squared. At 5 feet 9 inches (69 inches) and 160 pounds: 703 × 160 = 112,480, and 69 × 69 = 4,761, so the BMI is 112,480 ÷ 4,761, about 23.6.
What is a healthy weight for someone who is 5 feet 9 inches?
About 126 to 169 pounds, or 56.9 to 76.7 kg. That is the weight that gives a BMI of 18.5 to under 25 at that height. The table on this page lists the range for other heights.
Why are BMI thresholds lower for some ethnic groups?
People with a South Asian, Chinese, other Asian, Middle Eastern, Black African or African-Caribbean background tend to store more fat around the middle and face higher cardiometabolic risk at a lower BMI. NICE therefore counts overweight from a BMI of 23 and obesity from 27.5 in these groups. A WHO expert consultation in 2004 proposed the same action points for Asian populations.
Is BMI accurate for muscular people?
Not very. Muscle is denser than fat, so a 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 suggests the waist-to-height ratio as a check that works for them too.