AnyTool
Your files never leave your device. All processing happens locally in your browser.

How do I calculate my BMI from my height and weight?

Enter your height and weight into AnyTool BMI Calculator in metric (cm / kg) or imperial (ft·in / lb). It instantly shows your Body Mass Index, your WHO weight category on a colour-coded gauge, your healthy-weight range for that height, plus BMI Prime and the Ponderal Index. You can switch to the WHO Asia-Pacific (Asian) cut-offs, and everything is calculated in your browser, so nothing is uploaded.

  • BMI = weight(kg) ÷ height(m)², or 703 × lb ÷ in² in imperial
  • Live WHO category with class I/II/III obesity on a visual gauge
  • Optional WHO Asia-Pacific standard (overweight ≥ 23, obese ≥ 27.5)
  • Shows your healthy-weight range, BMI Prime and Ponderal Index
  • 100% in your browser — no upload, no signup, works offline

What is

Body Mass Index (BMI)

Body Mass Index is a screening number that estimates body fatness from height and weight, defined as mass in kilograms divided by the square of height in metres (kg/m²). The WHO classifies adults as underweight below 18.5, normal from 18.5 to 24.9, overweight from 25 to 29.9, and obese at 30 and above; the WHO Asia-Pacific standard lowers the overweight and obese cut-offs to 23 and 27.5.

Calculators

Related terms

Healthy weight rangeBMI PrimePonderal IndexWHO Asia-Pacific cut-offs

Frequently Asked Questions

BMI is your weight in kilograms divided by your height in metres squared. In imperial it is 703 times pounds divided by inches squared.

BMI equals mass divided by height squared: in metric that is kilograms ÷ (metres × metres), so a 70 kg person who is 1.75 m tall has a BMI of 70 ÷ (1.75 × 1.75) ≈ 22.9. The imperial form gives the same number using 703 × pounds ÷ (inches × inches). AnyTool computes it both ways live as you type.

Under the WHO standard a BMI from 18.5 to 24.9 is the healthy range for most adults.

The World Health Organization classes a BMI of 18.5 to 24.9 as normal (healthy) weight, below 18.5 as underweight, 25 to 29.9 as overweight and 30 or more as obese. The WHO Asia-Pacific standard lowers these to a normal range of 18.5 to 22.9 because many Asian populations carry more body fat at a given BMI. AnyTool also shows the exact weight range that keeps you in the healthy band for your height.

At the same BMI, many Asian populations have more body fat and higher health risk, so WHO Asia-Pacific marks overweight at 23 and obese at 27.5.

The WHO Asia-Pacific (WPRO) standard lowers the thresholds to a BMI of 23 for increased risk and 27.5 for high risk, because at any given BMI people of many Asian backgrounds tend to have a higher percentage of body fat and develop type 2 diabetes and cardiovascular disease at a lower BMI than the global average. AnyTool offers this as a toggle alongside the standard WHO cut-offs.

BMI is a screening tool, not a diagnosis — and nothing is uploaded; every calculation runs in your browser.

BMI is a quick screening number that cannot tell muscle from fat or where fat is stored, so it overstates body fat in very muscular people and understates it in older adults; it is not used for pregnancy, and children use age- and sex-specific percentile charts instead. AnyTool BMI Calculator runs entirely in your browser, so your height and weight are never sent to a server and the page works offline.

Detailed Explanation

Methodology

How the BMI Calculator Works

AnyTool BMI Calculator computes Body Mass Index in the browser as mass divided by height squared. In metric it uses kilograms ÷ (height in metres)², with height entered in centimetres; in imperial it uses the algebraically identical 703 × pounds ÷ (height in inches)², where 703 is the exact unit-conversion constant. The full-precision BMI is then classified, and derived measures — the healthy-weight range, BMI Prime and the Ponderal Index — are calculated from the same height and weight. All arithmetic is pure client-side JavaScript shared through a unit-tested engine.

  • Metric: weight(kg) ÷ height(m)²; imperial: 703 × lb ÷ in²
  • Height entered in cm or feet+inches; weight in kg or lb
  • Classified live against the active standard with no Calculate button
  • Healthy-weight range solves the normal BMI band for your height
  • All math is client-side JavaScript — no server round-trip
How It Works

WHO and WHO Asia-Pacific Classification

The default WHO adult standard classes BMI below 18.5 as underweight, 18.5–24.9 as normal, 25–29.9 as overweight, and 30+ as obese, further split into Class I (30–34.9), Class II (35–39.9) and Class III (40+). A toggle switches to the WHO Asia-Pacific (WPRO) standard, which lowers the overweight cut-off to 23 and the obese cut-off to 27.5 because, at a given BMI, many Asian populations carry a higher percentage of body fat and develop diabetes and cardiovascular disease at a lower BMI. The chosen standard drives both the category and the healthy-weight range, and a colour-coded gauge plots the result with the healthy band outlined.

  • WHO: underweight <18.5, normal 18.5–24.9, overweight 25–29.9, obese 30+
  • Obesity split into Class I, II and III at 35 and 40
  • WHO Asia-Pacific cut-offs: overweight ≥ 23, obese ≥ 27.5
  • Standard also adjusts the healthy-weight range it reports
  • Visual gauge shows exactly where the BMI falls
Limitations

BMI Is a Screening Tool, Not a Diagnosis

BMI estimates body fatness from height and weight alone and cannot distinguish muscle from fat or show fat distribution, so it overstates body fat in very muscular people and understates it in older adults who have lost muscle. It is not validated for pregnancy, and for children and teens (ages 2–19) BMI must be read against age- and sex-specific percentile charts rather than these fixed adult cut-offs. AnyTool states these limits plainly and presents the result as a starting point for a conversation with a clinician, who can add waist circumference and body-fat measurement.

  • Cannot separate muscle from fat or show where fat is stored
  • Overstates fat in athletes; understates it in older adults
  • Not used for pregnancy; children use BMI-for-age percentiles
  • Best paired with waist circumference and clinical context
  • Presented as a screen, not a diagnosis
Privacy & Security

Privacy and Offline Use

Because all computation runs in the browser, your height and weight are never sent to a server, there is no account or tracking, and the page works offline after first load. The calculator is built on a shared, unit-tested BMI engine so its behaviour is consistent and verifiable.

BMI calculation: in-browser (AnyTool) vs typical online BMI calculators
CapabilityAnyToolTypical online calculators
ProcessingRuns in your browserOften server-side
UnitsMetric and imperial, liveUsually one at a time
StandardsWHO + WHO Asia-Pacific toggleUsually WHO only
Obesity detailClass I / II / IIIOften a single "obese"
Visual gaugeColour-coded with healthy bandOften text only
Extra metricsHealthy range, BMI Prime, Ponderal IndexFrequently BMI only
Works offlineYes (PWA)No
Cost / signupFree, no signupOften ad-heavy or gated

AnyTool computes BMI and every derived metric locally and uploads nothing.