What is the BMI Calculator?
The BMI Calculator estimates your body mass index from your weight in kilograms and your height in centimetres. BMI divides weight by height squared and places the result in a standard category: underweight, normal, overweight or obese. It is a simple screening number often used by health professionals to start a conversation about weight.
How to use the BMI Calculator
- Enter your weight in kilograms.
- Enter your height in centimetres.
- Read your BMI value and category in the result box.
- Change the numbers to see how a different weight would affect your result.
Benefits and use cases
- People setting a general health or fitness goal.
- Gym members and runners tracking changes over time.
- Adults who want a quick reference figure before talking to a doctor.
- Anyone preparing a medical or insurance form that asks for BMI.
Tips for best results
Measure your height without shoes and weigh yourself at a similar time of day for consistent readings. Treat the number as one piece of information, along with waist size, fitness, diet and family history. If your result is outside the normal range, a doctor or dietitian can give advice that fits your body, age and lifestyle.
ToolZen tools run in your browser, so your input is not uploaded to a server. Bookmark this page and come back whenever you need it. There is nothing to install and no account to create.
Frequently asked questions
What are the BMI categories?
Below 18.5 is underweight, 18.5 to 24.9 is normal, 25 to 29.9 is overweight and 30 or more is obese.
Is BMI always accurate?
No. It does not separate muscle from fat, so athletes and older adults may get misleading results.
Can I use this for children?
This tool uses adult categories. Children and teenagers should be assessed with age and sex based charts by a doctor.
Should I rely on this for medical advice?
No. It is for information only, so please speak to a healthcare professional about your health.