Find your exact age in years, months and days from your date of birth, plus your age in days, weeks and hours and the days to your next birthday.
BMI Calculator
Calculate adult BMI from metric or imperial measurements and compare WHO or Asian/Indian category cut-offs.
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Body mass index
Healthy weight range at this height
Formula
BMI is a screening number for adults, not a diagnosis. It does not measure body fat and is not suitable for children, teenagers or pregnancy.
Runs entirely in your browser. Your files and text are not uploaded.
How to use BMI Calculator
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Step 1: Choose your units
Enter height in centimetres or feet and inches, and weight in kilograms or pounds.
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Step 2: Choose a category scale
Use WHO international cut-offs or Asian/Indian adult cut-offs with lower risk thresholds.
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Step 3: Read the result
Use the BMI and healthy-weight range as a starting point for a health conversation, not as a diagnosis.
BMI formula
Body mass index, or BMI, is weight in kilograms divided by height in metres squared. The calculator converts pounds and feet-and-inches to metric units before applying that formula. It then rounds the result to one decimal place.
For adults, the WHO international categories describe BMI below 18.5 as underweight, 18.5 to below 25 as the healthy range, 25 to below 30 as overweight, and 30 or more as the obesity range. Asian and Indian guidance uses lower thresholds because health risks can appear at lower BMI values for some populations. In that scale, the at-risk range begins at 23 and the obesity range at 25.
What BMI can and cannot show
BMI is a screening number, not a measure of body fat. It does not show where fat is stored, muscle mass, fitness, diet or blood pressure. A muscular person can have a high BMI without excess body fat, while an older person can have a BMI in the usual range with less muscle.
The healthy-weight range in this tool is the weight that corresponds to a BMI of 18.5 up to the upper limit of the selected scale at your height. It is not a personal target. Waist circumference, medical history and laboratory results can add useful context.
BMI cut-offs in this calculator are for adults aged 18 and over. Children and teenagers need age- and sex-specific growth charts. Pregnancy changes weight in ways that BMI does not describe well. If you are concerned about weight, eating, exercise or symptoms, speak with a qualified health professional.
Limitations
- BMI is a screening measure, not a diagnosis of health or body fat.
- It can be misleading for muscular people, older adults and some ethnic groups.
- It is not for children, teenagers or pregnancy.
- The category scales are general adult cut-offs, not personalised medical advice.
Frequently asked questions
Which BMI scale should I choose?
WHO is the common international adult scale. The Asian/Indian option has lower risk thresholds and may be useful when that context applies to you.
Does a healthy BMI mean I am healthy?
Not by itself. BMI does not measure body fat distribution, blood pressure, fitness or many other health factors.
Why does the calculator show a weight range?
It converts the selected healthy BMI range back into weights for your entered height. It is not a personal treatment target.
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