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BMI Calculator

Global tools

Enter a weight and a height - kilograms and centimeters, or pounds, feet and inches - and the page gives your BMI, the category it falls into on two official scales, the weight band a healthy BMI corresponds to at your height, and a table of what other weights would read as.

BMI Calculator - Danfio

https://danfio.com/tools/bmi-calculator/ - printed from this page

Metric takes kilograms and centimeters; imperial takes pounds, feet and inches.

Body weight in kilograms. BMI is a ratio of weight to height, not a body-fat measurement.

Height in centimeters. The healthy weight band is worked out at this height.

Leave blank to name the files bmi-calculation.txt and .csv.

Results update as you type. Nothing leaves your device.

BMI for 78 kg at 178 cm

24.6

WHO scale: Healthy range. Asia-Pacific scale: Increased risk.

Weight
78 kg 172 lb
Height
178 cm 5 ft 10.1 in
WHO category
Healthy range BMI 18.5 to 24.9
Asia-Pacific category
Increased risk BMI 23 to 24.9
Healthy weight band at this height
58.6–78.9 kg BMI 18.5 to 24.9
Inside the band
nothing to change this BMI is inside the healthy range

What other weights would read as, at this height

BMIWeightCategoryChange from now
18.558.6 kgHealthy−19.4 kg
2269.7 kgHealthy−8.3 kg
2372.9 kgHealthy / increased risk−5.1 kg
2579.2 kgOverweight+1.2 kg
27.587.1 kgOverweight+9.1 kg
3095.1 kgObesity+17.1 kg
35110.9 kgObesity+32.9 kg

The BMI boundaries turned into weights at this height, which is how most people actually think about them. 23 and 25 are the two overweight lines; 30 is where obesity starts on both scales.

The two scales, side by side

BMI rangeWHO categoryAsia-Pacific category
Under 18.5UnderweightUnderweight
18.5 to 22.9Healthy rangeHealthy range
23 to 24.9Healthy rangeIncreased risk
25 to 29.9OverweightObesity class I
30 to 34.9Obesity class IObesity class II
35 to 39.9Obesity class IIObesity class II
40 and overObesity class IIIObesity class II

Two official scales, disagreeing on purpose: the WHO Asia-Pacific cut-offs sit lower because the risk of type 2 diabetes and cardiovascular disease rises at a lower BMI in South and East Asian populations.

What this number is, and is not

  • BMI is a ratio of weight to height squared, and it does not know what the weight is made of: muscle, bone, fat and water all count the same. A muscular athlete can read as overweight while carrying very little fat.
  • It does not know where any fat is either. Fat around the waist carries more risk than fat on the hips at the same BMI, which is why waist measurement is used alongside it rather than instead of it.
  • It was designed for populations rather than individuals: it came from actuarial data across large groups, and it is a screening tool for flagging who might benefit from a closer look rather than a diagnosis or a target.
  • For children and teenagers, and during pregnancy, the bands are different and depend on age and sex. The adult numbers on this page do not apply to either.
This page does arithmetic on numbers you type. It cannot see you, it does not know your body composition, your medical history or your circumstances, and nothing here is medical advice. If a reading worries you, take it to a clinician who can measure what it cannot.

Two scales rather than one, because they disagree and both are in use. The WHO cut-offs put overweight at 25; the WHO Asia-Pacific cut-offs, published in 2004, put the increased-risk band at 23 and obesity at 25, because the risk of type 2 diabetes and cardiovascular disease rises at a lower BMI in South and East Asian populations. Both are applied to the same number so the difference is visible.

BMI is a screening measure rather than a diagnosis. It is a ratio, so it cannot tell muscle from fat, and it says nothing about where any fat sits - which is why waist measurement is used alongside it. The page says that outright rather than leaving it to a footnote.

About this bmi calculator

Officially there are two body mass index scales, and this page prints both instead of choosing: the WHO cut-offs that put overweight at 25, and the WHO Asia-Pacific cut-offs that raise the risk band at 23. Where the two disagree, the visitor can see why.

Nothing you type is sent anywhere: the height and weight are used by a small fixed calculation in the browser, no account is needed to open the page, and the calculation is the same one that built the static result. Two official tables are run on the same number so the difference between them is visible rather than asserted.

It says nothing about muscle or where fat sits, and it does not apply to children, teenagers or pregnancy, who are assessed on age- and sex-specific charts. What it does is a screening ratio for height and weight, computed from the numbers you enter. Read the band as a starting point and bring the waist tape to the conversation. Not a medical device and not a diagnosis; talk to a clinician.

How this bmi calculator works

The formula, and what it leaves out

BMI is weight in kilograms divided by height in meters squared. At 78 kg and 178 cm that is 78 ÷ (1.78 × 1.78) = 24.6. The imperial version is the same definition with a conversion factor folded in (pounds × 703 ÷ inches²), which is why the page converts the units first rather than using a second formula that could drift from this one.

What the formula leaves out is everything that is not height and weight. Muscle is denser than fat, so a rugby player and a sedentary person of the same height and weight share a BMI and have very different bodies. Bone density, water and age-related muscle loss all move the same way: the ratio stays put while the body changes.

Where fat sits matters too, and BMI cannot see it. Waist circumference adds that information, which is why public health guidance pairs the two measures rather than choosing between them.

Where the cut-offs came from, and why there are two sets

The 25 and 30 thresholds come from actuarial and epidemiological data linking BMI to mortality in largely European and American populations. They are conventions that proved useful rather than physical constants: nothing changes in a body at exactly 24.9.

The Asia-Pacific cut-offs exist because that data does not transfer. At the same BMI, people of South and East Asian descent tend to carry more visceral fat and face higher risk of type 2 diabetes at lower body weights, so the WHO published lower thresholds in 2004. A BMI of 24 is "healthy" on one scale and "increased risk" on the other, and both are true within their own frame.

For children and teenagers there is no single cut-off at all: BMI is compared against age- and sex-specific centile charts, because a growing body changes shape continuously. Adult numbers, including these, do not apply.

The healthy weight band, which is more useful than the category

The healthy BMI range of 18.5 to 24.9 turned into weights at a given height gives a band rather than a target: at 178 cm it is roughly 58.6 kg to 78.9 kg, and any weight inside it reads as healthy on the WHO scale. That is a span of more than 20 kg, which is a useful reminder that the number marks a range, not a point.

The weight table turns the boundaries into the form people actually use: what 23, 25 or 30 would weigh at this height, and how far that is from where they are now. The direction of the difference is stated, and it points both ways - a BMI of 17 shows weight to gain rather than to lose.

What this page will not do

It will not tell you whether you are healthy. It does not know your blood pressure, your blood sugar, your waist measurement, your fitness, your diet, your history or your age, and BMI alone is a weak predictor of any individual outcome.

It also will not set a target weight. A weight that is right for one person at a given height is not right for another, and a page that converted "healthy BMI" into a goal weight would be encouraging exactly the use of this number that clinicians warn against. The band is information; what to do with it is a conversation with somebody who can measure more than a ratio.

Worked examples

Each example below was run through the calculator on this page when the site was built, so the numbers match what you see when you enter the same inputs.

78 kg at 178 cm

Units: Metric (kg, cm) · Weight: 78 kg · Height: 178 cm

BMI for 78 kg at 178 cm

24.6

WHO scale: Healthy range. Asia-Pacific scale: Increased risk.

Weight: 78 kg · Height: 178 cm · WHO category: Healthy range · Asia-Pacific category: Increased risk

BMI 24.6: inside the healthy range on the WHO scale, and just inside the Asia-Pacific increased-risk band, which starts at 23. The healthy band at this height is 58.6 to 78.9 kg.

The same person in pounds and feet

Units: Imperial (lb, feet and inches) · Weight: 172 lb · Height: 5 ft · and: 10 in

BMI for 78 kg at 177.8 cm

24.7

WHO scale: Healthy range. Asia-Pacific scale: Increased risk.

Weight: 78 kg · Height: 177.8 cm · WHO category: Healthy range · Asia-Pacific category: Increased risk

172 lb and 5 ft 10 in gives 24.7 - the same body measured in the units its owner happens to think in. The conversion happens before the arithmetic, not after it.

A muscular 90 kg at 178 cm

Units: Metric (kg, cm) · Weight: 90 kg · Height: 178 cm

BMI for 90 kg at 178 cm

28.4

WHO scale: Overweight. Asia-Pacific scale: Obesity class I.

Weight: 90 kg · Height: 178 cm · WHO category: Overweight · Asia-Pacific category: Obesity class I

BMI 28.4, which reads as overweight on both scales - and may be almost entirely muscle. This is the case the number cannot see, and the reason the page refuses to call it a diagnosis.

A weight below the band

Units: Metric (kg, cm) · Weight: 55 kg · Height: 178 cm

BMI for 55 kg at 178 cm

17.4

WHO scale: Underweight. Asia-Pacific scale: Underweight - the two agree at this number.

Weight: 55 kg · Height: 178 cm · WHO category: Underweight · Asia-Pacific category: Underweight

BMI 17.4, underweight, with 3.6 kg to gain to reach the bottom of the healthy band. The page points in both directions rather than assuming everybody is trying to lose weight.

Frequently asked questions

What is a healthy BMI?

Between 18.5 and 24.9 on the WHO scale, or 18.5 to 22.9 on the WHO Asia-Pacific scale for people of South and East Asian descent. Both are ranges rather than targets: at 178 cm the WHO band spans about 20 kg of body weight, which is a reminder of how coarse a single number is.

Why does this calculator show two different categories?

Because two official scales exist and they disagree between 23 and 30. The WHO cut-offs came from data in largely European and American populations; the Asia-Pacific cut-offs were published in 2004 because risk rises at a lower BMI in South and East Asian populations. The page applies both to your number rather than choosing for you.

Is BMI accurate for muscular people?

No, and it is not meant to be. BMI cannot distinguish muscle from fat, so a heavily muscled athlete often reads as overweight while carrying less fat than an average person of the same height. Waist measurement, a body-composition measurement, or a clinician who can see the difference are what to use instead.

What is my ideal weight?

The page gives a healthy band rather than an ideal weight, deliberately: any weight inside the band reads the same, and which end of it suits a particular person depends on muscle, frame and circumstance. A "goal weight" produced by a BMI calculator is a number invented by arithmetic, not a medical target.

Do the adult BMI cut-offs apply to children?

No. Children and teenagers are assessed against age- and sex-specific growth charts, because a growing body changes shape continuously and a fixed cut-off would classify normal development as abnormal. The same applies during pregnancy, where BMI bands are not used to assess weight.

Is BMI still used by doctors?

Yes, as a first screening measure, usually alongside waist circumference and other risk factors. It is quick, it needs nothing but a scale and a tape measure, and it correlates with health outcomes across populations - which is exactly why it is useful for populations and limited for individuals.

Which is better, BMI or waist measurement?

They answer different questions: BMI says how heavy somebody is for their height, waist measurement says where the weight sits. Abdominal fat carries more metabolic risk at the same BMI, so the two are used together. If you want one number and have a tape measure, waist-to-height ratio is the more direct indicator.

Assumptions and sources

  • World Health Organization, Obesity: preventing and managing the global epidemic (WHO Technical Report Series 894, 2000): the BMI categories used on the WHO scale here.
  • WHO Expert Consultation, Appropriate body-mass index for Asian populations and its implications for policy and intervention strategies, The Lancet 363 (2004): the Asia-Pacific cut-offs at 23 and 25.
  • US Centers for Disease Control and Prevention, About Adult BMI: BMI as a screening measure, its limits for muscular individuals, and the use of waist circumference alongside it.
  • CDC and WHO guidance that BMI for children and adolescents is assessed against age- and sex-specific percentile charts rather than fixed cut-offs.
  • Both scales are printed side by side because they disagree at 23 and 25, and a BMI is a screening measure rather than a diagnosis.

Last reviewed 2026-09-15. Not a medical device and not a diagnosis; talk to a clinician. Read the full disclaimer.

Where a figure on this page comes from an official agency — HUD, IRS, FICO or a state body — the site keeps a dated snapshot of the source page in its sources library, and a scheduled job re-checks that snapshot, so the number can be traced back to the document it came from.

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