BMI Calculator: Body Mass Index and Healthy Weight for Your Height
BMI Calculator
Work out your body mass index from your height and weight, in feet and pounds or in centimetres and kilograms, and see what it means: the category it falls in, the healthy weight range for your height, how far you are from it, and where you sit on the chart everyone else is measured against. Add your waist and the page also gives your waist to height ratio, which picks up the belly fat that BMI cannot see.
Where your BMI falls
You on the height and weight chart
BMI is weight in kilograms divided by the square of height in metres, or 703 times weight in pounds divided by the square of height in inches. The categories are the adult ones used by the World Health Organization and the CDC, for people aged 20 and over, whatever their sex or age: under 18.5 underweight, 18.5 to 24.9 healthy, 25 to 29.9 overweight, and 30 and above obesity in three classes. BMI is a screening figure, not a diagnosis. It cannot tell muscle from fat, and the same number carries different risk in different bodies, so read it alongside your waist and a conversation with a clinician. For children and teenagers BMI is read against age and sex percentile charts instead. This is general information, not medical advice. The CSV, image and printed report contain the values you entered, nothing preloaded.
How to use this tool
Choose whether you measure height in feet and inches or in centimetres, type your height and weight, and the result appears as you go: the BMI and its category at the top, the healthy weight range for your height in the coloured cards, and the gauge, scale and chart below. Switching units converts what you have already typed, so you can read the same answer in the other system.
Measure without shoes and weigh in light clothing, ideally in the morning. Height matters more than it looks: BMI divides by it twice, so an inch of error in height moves the result about as much as five or six pounds on the scale. The waist and age boxes are optional. Give your waist, measured around the navel, and the page adds your waist to height ratio. Give your age and the page will tell you if the adult categories do not apply.
What the calculation is doing
Body mass index is weight divided by the square of height. The Belgian statistician Adolphe Quetelet noticed in the 1830s that across adults weight rose roughly with the square of height, and in 1972 the physiologist Ancel Keys named the ratio body mass index and showed it tracked body fat better than the other simple height and weight indices then in use. It has been the standard population screening measure ever since.
In metric units it is kilograms divided by metres squared. In pounds and inches the arithmetic gives a number about 703 times too small, so the formula carries a factor of 703, or 703.07 exactly, to land on the same scale. That is the only difference between the two versions.
The adult categories
These are the categories the World Health Organization and the CDC use for adults aged 20 and over, the same for men and women and for every adult age. The weights show what each band means in practice at three common heights.
| Category | BMI | At 5 ft 4 in | At 5 ft 10 in | At 175 cm |
|---|---|---|---|---|
| Underweight | below 18.5 | under 108 lb | under 129 lb | under 57 kg |
| Healthy weight | 18.5 to 24.9 | 108 to 145 lb | 129 to 173 lb | 57 to 76 kg |
| Overweight | 25 to 29.9 | 146 to 174 lb | 174 to 208 lb | 77 to 91 kg |
| Obesity, class 1 | 30 to 34.9 | 175 to 203 lb | 209 to 243 lb | 92 to 107 kg |
| Obesity, class 2 | 35 to 39.9 | 204 to 232 lb | 244 to 278 lb | 108 to 122 kg |
| Obesity, class 3 | 40 and above | 233 lb and up | 279 lb and up | 123 kg and up |
Whole pounds and kilograms, placed by the BMI rounded to one decimal, the way the CDC reports it, so the ranges meet without gaps.
Healthy weight by height
The healthy range is a BMI of 18.5 to 24.9, so at any height it runs from 18.5 times height squared to 24.9 times height squared. The table gives it for every inch from 4 ft 10 in to 6 ft 6 in, with the weight at which BMI reaches 30.
| Height | Healthy weight, lb | Healthy weight, kg | BMI 30 at |
|---|---|---|---|
| 4 ft 10 in | 89 to 119 | 40.2 to 54 | 144 lb |
| 4 ft 11 in | 92 to 123 | 41.5 to 55.9 | 149 lb |
| 5 ft 0 in | 95 to 127 | 43 to 57.8 | 154 lb |
| 5 ft 1 in | 98 to 132 | 44.4 to 59.8 | 159 lb |
| 5 ft 2 in | 101 to 136 | 45.9 to 61.8 | 164 lb |
| 5 ft 3 in | 105 to 140 | 47.4 to 63.8 | 169 lb |
| 5 ft 4 in | 108 to 145 | 48.9 to 65.8 | 175 lb |
| 5 ft 5 in | 111 to 149 | 50.4 to 67.9 | 180 lb |
| 5 ft 6 in | 115 to 154 | 52 to 70 | 186 lb |
| 5 ft 7 in | 118 to 159 | 53.6 to 72.1 | 192 lb |
| 5 ft 8 in | 122 to 164 | 55.2 to 74.3 | 197 lb |
| 5 ft 9 in | 125 to 168 | 56.8 to 76.5 | 203 lb |
| 5 ft 10 in | 129 to 173 | 58.5 to 78.7 | 209 lb |
| 5 ft 11 in | 133 to 178 | 60.2 to 81 | 215 lb |
| 6 ft 0 in | 137 to 183 | 61.9 to 83.3 | 221 lb |
| 6 ft 1 in | 140 to 189 | 63.6 to 85.6 | 227 lb |
| 6 ft 2 in | 144 to 194 | 65.4 to 88 | 234 lb |
| 6 ft 3 in | 148 to 199 | 67.1 to 90.4 | 240 lb |
| 6 ft 4 in | 152 to 204 | 68.9 to 92.8 | 246 lb |
| 6 ft 5 in | 156 to 210 | 70.8 to 95.2 | 253 lb |
| 6 ft 6 in | 160 to 215 | 72.6 to 97.7 | 260 lb |
For adults aged 20 and over. Each height opens the calculator on the healthy range for that height.
BMI chart
The classic chart, in pounds. Find your height down the side and your weight across the top; the nearest cell gives your BMI to one decimal.
| Height | 100 lb | 125 lb | 150 lb | 175 lb | 200 lb | 225 lb | 250 lb | 275 lb | 300 lb |
|---|---|---|---|---|---|---|---|---|---|
| 4 ft 10 in | 20.9 | 26.1 | 31.3 | 36.6 | 41.8 | 47.0 | 52.2 | 57.5 | 62.7 |
| 5 ft 0 in | 19.5 | 24.4 | 29.3 | 34.2 | 39.1 | 43.9 | 48.8 | 53.7 | 58.6 |
| 5 ft 2 in | 18.3 | 22.9 | 27.4 | 32.0 | 36.6 | 41.2 | 45.7 | 50.3 | 54.9 |
| 5 ft 4 in | 17.2 | 21.5 | 25.7 | 30.0 | 34.3 | 38.6 | 42.9 | 47.2 | 51.5 |
| 5 ft 6 in | 16.1 | 20.2 | 24.2 | 28.2 | 32.3 | 36.3 | 40.4 | 44.4 | 48.4 |
| 5 ft 8 in | 15.2 | 19.0 | 22.8 | 26.6 | 30.4 | 34.2 | 38.0 | 41.8 | 45.6 |
| 5 ft 10 in | 14.3 | 17.9 | 21.5 | 25.1 | 28.7 | 32.3 | 35.9 | 39.5 | 43.0 |
| 6 ft 0 in | 13.6 | 17.0 | 20.3 | 23.7 | 27.1 | 30.5 | 33.9 | 37.3 | 40.7 |
| 6 ft 2 in | 12.8 | 16.0 | 19.3 | 22.5 | 25.7 | 28.9 | 32.1 | 35.3 | 38.5 |
| 6 ft 4 in | 12.2 | 15.2 | 18.3 | 21.3 | 24.3 | 27.4 | 30.4 | 33.5 | 36.5 |
| 6 ft 6 in | 11.6 | 14.4 | 17.3 | 20.2 | 23.1 | 26.0 | 28.9 | 31.8 | 34.7 |
Shaded by category: blue underweight, teal healthy, amber overweight, orange and red the three obesity classes. Every value is a link to that height and weight.
Why height is squared, and why some say it should not be
If people were simply scaled up versions of each other, weight would rise with the cube of height, not the square. They are not: taller adults are, on average, proportionally slimmer, and across real populations the square fits better than the cube, which is why Quetelet chose it.
It is not a perfect fit either. The Oxford mathematician Nick Trefethen pointed out in 2013 that the square overstates body fat in tall people and understates it in short ones, and proposed 1.3 times weight over height to the power 2.5 instead, scaled so that it matches the ordinary BMI for someone of average height. The page shows that figure too. For most people the two agree within a point; at 6 ft 4 in or 5 ft 0 in the gap is worth knowing about when you are close to a boundary.
A worked check you can repeat on paper
Take the page’s starting values: 5 ft 10 in and 180 lb. Height is 70 inches, and 70 squared is 4,900. Weight divided by that is 180 over 4,900, or 0.036735. Multiply by 703 and you get 25.8, which is overweight, just past the line at 25.
In metric the same person is 81.65 kg and 1.778 m. The height squared is 3.1613, and 81.65 divided by 3.1613 is 25.8 again. The healthy range at this height is 18.5 times 3.1613 to 24.9 times 3.1613, which is 58.5 to 78.7 kg or 129 to 173 lb, so this person is 6.5 lb above the top of it.
A useful rule of thumb falls out of this: at 5 ft 10 in, each point of BMI is about 7 lb. At 5 ft 4 in it is about 5.8 lb, and at 6 ft 2 in about 7.8.
What BMI misses, and what to add
Muscle. BMI cannot tell a kilogram of muscle from a kilogram of fat. Strength athletes and heavy manual workers often read as overweight or obese while carrying little fat. For them the number is close to meaningless.
Where the fat sits. Fat carried around the organs is linked to diabetes and heart disease more strongly than fat elsewhere, and it can be present at a normal BMI. Waist to height ratio picks it up. NICE advises keeping your waist below half your height, and treats 0.5 to 0.59 as increased risk and 0.6 or more as high risk.
Ethnic background. At the same BMI, the risk of type 2 diabetes is higher in people of South Asian, Chinese, other Asian, Middle Eastern, Black African and African Caribbean family background. NICE recommends using 23 as the threshold for overweight and 27.5 for obesity in those groups.
Age. Muscle is gradually lost with age and replaced by fat, often with little change on the scale, so the same BMI means more body fat at 70 than at 30. For children and teenagers the adult categories do not apply at all; BMI is read as a percentile on CDC growth charts for the exact age and sex.
Mistakes that catch people out
Measuring height in shoes, or rounding it to the nearest few inches. Because height is squared, a one inch overestimate at 5 ft 10 in pulls BMI down by about 0.7, enough to move someone across a boundary.
Weighing at the end of the day in clothes. Clothes, a meal and the day’s fluid can add three to five pounds. Weigh at the same time of day in the same clothing if you are tracking a trend.
Applying the adult categories to a teenager. A 15 year old with a BMI of 24 may be well above the healthy range for their age, or comfortably inside it, depending on sex and exact age. Use a percentile chart.
Reading a boundary too literally. 24.9 and 25.1 are the same body. The categories are a convenient way to summarise risk across millions of people, not a line where something changes.
Using BMI alone to judge an athlete. Add the waist measurement, or a body fat estimate, before drawing any conclusion.
Popular calculations
Each opens the calculator on that height and weight with its own address, and every value can be changed once it is open.
4 ft 10 in to 5 ft 3 in
5 ft 4 in to 5 ft 9 in
5 ft 10 in to 6 ft 6 in
Healthy weight by height
Metric
How this was checked
The engine was tested in Node against hand calculations in both unit systems before it went near the page: 5 ft 10 in and 180 lb gives 25.827 by the metric definition and 25.827 with the 703.07 factor, which is the same number to the precision either can carry. The healthy ranges were checked against the definition at every height in the table, and every whole pound and kilogram was placed by its BMI rounded to one decimal, the way the CDC reports it, so the ranges meet without gaps or overlaps. The category boundaries were tested either side of each cutoff, at 24.94 and 24.96 for example, which round to 24.9 and 25.0 and fall in different categories.
Every address in the lists above was then opened and checked for a distinct title, the right answer, charts that render, and clean CSV, image and print output containing only that calculation, at desktop, tablet and phone widths.
Common questions
What is a healthy BMI?
For adults aged 20 and over, a BMI of 18.5 to 24.9 is the healthy range used by the World Health Organization and the CDC. Under 18.5 is underweight, 25 to 29.9 is overweight, and 30 and above is obesity, split into class 1 from 30, class 2 from 35 and class 3 from 40. The same ranges apply to men and women of every adult age.
How do I calculate BMI by hand?
Divide your weight in kilograms by your height in metres squared. In pounds and inches, divide weight by height in inches squared and multiply by 703. At 5 ft 10 in and 180 lb that is 180 divided by 4,900, times 703, which is 25.8.
What is a healthy weight for 5 ft 4 in?
108 to 145 pounds, which is 48.9 to 65.8 kilograms. For 5 ft 10 in it is 129 to 173 pounds. The table of healthy weight by height on this page covers every inch from 4 ft 10 in to 6 ft 6 in.
Is BMI accurate for muscular people?
No. BMI only knows weight and height, and muscle is heavy, so a lean, well trained person can read as overweight or even obese. For them a waist measurement or a body fat estimate says much more. BMI is most useful for people who are not unusually muscular, and for tracking the same person over time.
Is BMI different for men and women, or with age?
Not for adults. The same categories apply to both sexes and to every age from 20 up, even though women carry more body fat than men at the same BMI and older adults carry more fat than younger ones. For children and teenagers BMI is read against CDC growth charts for their exact age and sex, as a percentile.
What is a good waist to height ratio?
Below 0.5, which means keeping your waist under half your height. NICE in the UK treats 0.5 to 0.59 as increased health risk and 0.6 or more as high. It catches fat carried around the middle that BMI misses, and it works across heights, sexes and most ethnic backgrounds.
Related Calculators and Reference
- Body Fat Calculator: the next step when BMI and your waist disagree, from a tape measure.
- TDEE Calculator: how many calories your body uses in a day, the starting point for changing your weight.
- Macro Calculator: protein, carbohydrate and fat targets once you know your calories.
- Kilograms to Pounds: for switching weights between the two systems.
- Feet to Centimetres: for converting height before you start.
- BMR Calculator: the resting figure at the bottom of your daily burn, on five equations.
- Calorie Deficit Calculator: a daily calorie target and a realistic date for a goal weight.
- Water Intake Calculator: how much to drink a day, with extra for exercise and heat.
- Ideal Weight Calculator: ideal body weight for your height.
- Heart Rate Zone Calculator: training zones from your age.
- Due Date Calculator: pregnancy due date, trimesters and key weeks.
- Waist to Hip Ratio Calculator: waist to hip and waist to height ratios, the fat distribution measures BMI cannot show.
- Lean Body Mass Calculator: lean mass and fat mass from height, weight and sex.
- Pregnancy Weight Gain Calculator: the recommended weight gain range for your pre pregnancy BMI class.
- CDC adult BMI categories: the category definitions this page uses.