Healthy under both standards
- Input
- 70 kg, 175 cm
- Output
- BMI 22.9 — healthy
Comfortably inside both the WHO band (18.5–24.9) and the Asian band (18.5–22.9), though only just under the latter.
BMI Calculator
A BMI calculator compares weight against height to give a single screening figure. Which thresholds it judges you against matters as much as the number: the WHO international cut-offs place the healthy band at 18.5–24.9, but the WHO expert consultation found cardiometabolic risk rises at a lower BMI in South and East Asian populations, and Indian, Chinese and Japanese guidelines use 23 and 27.5 accordingly. Both standards are offered here.
Runs entirely in your browser — your figures are never uploaded.
How is BMI calculated?
BMI is weight in kilograms divided by height in metres squared. Someone 70 kg and 1.75 m tall has a BMI of 22.9. WHO classifies 18.5–24.9 as healthy, but Indian and East Asian guidelines use 18.5–22.9 because risk rises at a lower BMI.
BMI is a screening measure, not a diagnosis. It cannot assess individual health. Speak to a doctor or dietitian about your own circumstances.
kg
cm
Body mass index
22.9
Healthy weight
- Underweight0–18.4
- Healthy weight18.5–24.9
- Overweight25–29.9
- Obese30+
- Healthy weight for your height
- 56.7–76.6 kg
- Your category
- Healthy weight
Under WHO thresholds
The maths
BMI Calculator formula
Formula
BMI = weight (kg) / height (m)²
- weight
- Body mass in kilograms
- height
- Height in metres — centimetres divided by 100
Worked example
Someone weighing 70 kg and standing 175 cm tall
Inputs
- Weight
- 70 kg
- Height
- 175 cm = 1.75 m
Working
- height² = 1.75 × 1.75 = 3.0625
- BMI = 70 ÷ 3.0625
BMI 22.9 — healthy under both WHO and Asian thresholds. At 74 kg the same person is 24.2: still healthy by WHO, but 'increased risk' by Asian guidelines.
How to
How to use the BMI Calculator
- 1
Choose your units
Enter height in centimetres and weight in kilograms, or switch to feet, inches and pounds. Conversion happens automatically.
- 2
Select the threshold set
Use WHO international cut-offs, or Asian cut-offs if you are of South or East Asian descent, where several national guidelines set lower boundaries.
- 3
Read your category
The result shows your BMI with the band it falls into and the exact boundaries, so you can see how close you are to the next one.
- 4
Check the healthy range
The weight range corresponding to a healthy BMI at your height is more actionable than the index itself.
Reference
BMI categories under each standard
| Category | WHO international | Asian guidelines |
|---|---|---|
| Underweight | below 18.5 | below 18.5 |
| Healthy weight | 18.5 – 24.9 | 18.5 – 22.9 |
| Overweight / increased risk | 25.0 – 29.9 | 23.0 – 27.4 |
| Obese / high risk | 30.0 and above | 27.5 and above |
Examples
BMI Calculator examples
Where the standards disagree
- Input
- 73.5 kg, 175 cm
- Output
- WHO: healthy · Asian: increased risk
At BMI 24.0 the two guidelines give different answers. For someone of South Asian descent the lower threshold is the clinically relevant one.
Imperial input
- Input
- 154 lb, 5 ft 9 in
- Output
- BMI 22.7
Converted to 69.9 kg and 175.3 cm before the calculation. Entering imperial units does not change the formula.
Why use it
What the BMI Calculator gives you
The threshold set that applies to you
Offering Asian cut-offs matters because a calculator using only WHO bands tells a large share of the world's population they are fine when their own health service would not.
Boundaries shown, not just a label
Seeing the exact cut-offs makes it clear how close you are to a different category, which a single word cannot convey.
A healthy weight range
The weight range for your height is a more useful target than an index number with no units.
Private
Height and weight are never transmitted or stored.
Good to know
BMI Calculator limitations
- BMI does not distinguish muscle from fat. Athletes are routinely classified as overweight despite low body fat.
- It says nothing about fat distribution. Waist circumference is a better predictor of metabolic risk than BMI alone.
- It is a population screening tool, not a diagnosis. Individual health depends on many factors BMI does not measure.
- Not valid for children, pregnant women or the very elderly, who require age-specific or alternative measures.
Summary
BMI Calculator in short
- BMI = weight in kg ÷ height in metres squared.
- WHO places the healthy band at 18.5–24.9.
- Asian guidelines use 18.5–22.9, with high risk from 27.5.
- BMI cannot distinguish muscle from fat.
- Waist measurement adds information BMI does not capture.
FAQ
BMI Calculator questions
What is the BMI formula?
BMI = weight in kilograms divided by height in metres squared. For 70 kg at 1.75 m: 70 ÷ (1.75 × 1.75) = 22.9. In imperial units it is (pounds ÷ inches²) × 703.
Why are Asian BMI thresholds lower?
A WHO expert consultation published in The Lancet in 2004 found that cardiometabolic risk rises at a lower BMI in Asian populations, partly due to differences in body composition. India, China, Japan and Singapore use 23 and 27.5 as a result.
What is a healthy BMI?
18.5 to 24.9 under WHO international cut-offs, or 18.5 to 22.9 under Asian guidelines. Both are population ranges — an individual outside them is not automatically unhealthy, nor healthy inside them.
Is BMI accurate for muscular people?
No. Muscle is denser than fat, so athletes frequently register as overweight or obese despite low body fat. For anyone carrying substantial muscle, body fat percentage or waist measurement is more informative.
Is waist measurement better than BMI?
For metabolic risk, often yes. Fat around the abdomen carries more risk than the same weight elsewhere, and waist circumference captures that where BMI cannot. The two are commonly used together.
Does BMI work for children?
Not with adult thresholds. Children's BMI must be read against age and sex percentile charts because body composition changes throughout growth. Use a paediatric BMI-for-age chart instead.
How do I calculate BMI in pounds and inches?
BMI = (weight in pounds ÷ height in inches²) × 703. The 703 factor converts imperial units to the metric formula. This calculator does the conversion for you if you switch units.
How quickly can BMI change?
It tracks weight directly, so it moves as weight does. A safe rate of change is generally 0.25–0.5 kg a week, which for someone 175 cm tall shifts BMI by roughly 0.08–0.16 per week.
Is my height and weight recorded?
No. The calculation is a single division performed in your browser. Nothing is transmitted, and no health information is stored or logged anywhere.
Sources
- WHO, Body mass index
- WHO expert consultation, The Lancet 2004 — Asian BMI cut-offs
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