Calculators
BMI Calculator
Check your Body Mass Index from height and weight, with category and healthy weight range.
Enter your height and weight, then press Calculate BMI.
What is BMI?
Body Mass Index (BMI) is a simple number calculated from your height and weight that screens for weight categories which may be linked to health risks. The formula is weight in kilograms divided by height in metres squared. Health organizations worldwide use the same cut-offs: below 18.5 is underweight, 18.5 to 24.9 is normal, 25 to 29.9 is overweight, and 30 or above is obese. This calculator applies that standard formula and shows your category with a visual indicator, plus the healthy weight range for your height.
How to use this tool
- Choose your height unit: centimetres, or feet + inches.
- Enter your height and your weight in kilograms.
- Press Calculate BMI to see your BMI value, category, indicator bar, and healthy weight range.
- Press Clear to reset the fields.
Key features
- Two height input modes — centimetres or feet and inches — with the form adapting to your choice.
- Standard WHO BMI categories with a colour-coded indicator bar for instant visual reading.
- Personalized healthy weight range (18.5–24.9 × height²) so you see a target, not just a label.
- Honest disclaimer: BMI is a screening tool, not a diagnosis, and the result says so plainly.
- Fully private — your measurements never leave your browser.
Common use cases
- Personal health tracking: a quick monthly check alongside diet or exercise routines.
- Medical visits: knowing your BMI before a checkup helps you discuss it with your doctor.
- Fitness goals: converting a target BMI into a target weight range for your height.
- Insurance and employment medicals: many forms ask for BMI, and this gives you the exact figure.
- Parents: a rough sense of where a teenager's growth sits (though child BMI uses age-based percentiles — ask a paediatrician).
Practical tips
- Weigh yourself at the same time of day, ideally in the morning, for consistent tracking.
- BMI does not distinguish muscle from fat — a muscular athlete can score "overweight" while being very fit.
- For South Asian adults, some medical guidelines suggest paying attention from a BMI of 23 upward, as health risks can appear at lower BMIs — discuss this with your doctor.
- Track the trend over months rather than reacting to a single reading; daily weight fluctuates with water and meals.
- Waist circumference alongside BMI gives a fuller picture of health risk than either alone.
Frequently Asked Questions
How is BMI calculated?
Divide your weight in kilograms by the square of your height in metres. For example, 65 kg at 1.70 m gives 65 ÷ (1.70 × 1.70) = 22.5, which is in the normal range.
What are the BMI categories?
Below 18.5 is underweight, 18.5–24.9 is normal weight, 25–29.9 is overweight, and 30 or above is obese. These are the standard international cut-offs.
Is BMI accurate for everyone?
Not entirely. It can misclassify muscular athletes, pregnant women, children, and older adults with low muscle mass. Treat it as a screening measure and consult a doctor for personal advice.
How is the healthy weight range worked out?
It is the weight range that would put your BMI between 18.5 and 24.9 for your height — simply 18.5 × height² to 24.9 × height².
Does this tool save my height and weight?
No. Everything is calculated locally in your browser and nothing is transmitted or stored anywhere.