FotoBiteBMI calculator (body mass index)
BMI compares your weight with your height. The calculator works it out, names the WHO category and shows the healthy weight range for your height.
What you enter is not stored or shared: the maths runs in your browser, or on our server without saving anything if JavaScript is off.
Your BMI
Underweight
Healthy weight
Overweight (pre-obesity)
Obesity class I
Obesity class II
Obesity class III
Healthy weight for your height: – kg.
You are kg below the healthy range.
You are kg above the healthy range.
BMI cannot tell muscle from fat and ignores age, sex and build. It can read high in very muscular people and look normal in older people who carry extra fat. It is a guide, not a diagnosis.
To move your weight on purpose, it helps to see what you eat. Snap your food and FotoBite counts the calories and macros for the day.
Count calories from photos in TelegramNothing from this page is passed to Telegram.
How BMI is calculated
BMI is your weight in kilograms divided by the square of your height in metres: BMI = weight / height².
Example: 170 cm and 68 kg give 68 / (1.7 × 1.7) ≈ 23.5. That is a healthy weight, and the healthy range for this height is 53.5–72 kg.
The healthy weight range is worked out backwards: 18.5 × height² and 24.9 × height².
WHO BMI categories
| BMI | Category |
|---|---|
| below 18.5 | Underweight |
| 18.5–24.9 | Healthy weight |
| 25.0–29.9 | Overweight (pre-obesity) |
| 30.0–34.9 | Obesity class I |
| 35.0–39.9 | Obesity class II |
| 40 and above | Obesity class III |
Who it is for
The calculator and the WHO table are for adults aged 18 and over. Children and teenagers are assessed with growth charts by age and sex, and BMI does not apply in pregnancy.
What BMI does not show
BMI cannot tell muscle from fat and ignores age, sex and build. It can read high in very muscular people and look normal in older people who carry extra fat. It is a guide, not a diagnosis. If your BMI is outside the healthy range, talk to a doctor, who will look at other measures too.
Categories: World Health Organization, adult BMI classification (WHO, A healthy lifestyle: WHO recommendations).
Frequently asked questions
What is a healthy BMI?
For adults the WHO classes 18.5 to 24.9 as a healthy weight. 25 to 29.9 is overweight, and 30 or more is obesity.
How do I calculate BMI myself?
Divide your weight in kilograms by your height in metres squared. At 1.7 m and 68 kg that is 68 / 2.89 ≈ 23.5.
Why can BMI be misleading?
The formula only knows height and weight. It cannot tell muscle from fat, so athletes can have a high BMI with little body fat, and older people can have a normal BMI with extra fat.
Can children and teenagers use this calculator?
No. The WHO table is for adults; children and teenagers are assessed with growth charts by age and sex. A paediatrician is the right person to ask.
Is my data saved?
No. BMI is worked out in your browser and the numbers you enter are not sent anywhere. With JavaScript off the server does the maths: it stores nothing, and your details never appear in the page address.
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This is a guide, not medical advice. Talk to a doctor before changing your diet. The calculator and FotoBite are for adults, 18+.
Not for pregnant or breastfeeding women. If you have an eating disorder or a chronic condition, talk to your doctor first.
The calculator and the WHO table are for adults aged 18 and over. Children and teenagers are assessed with growth charts by age and sex, and BMI does not apply in pregnancy.