BMI Calculator Australia – Free BMI Calculator (kg & cm)
Use this free BMI calculator for Australia to check your body mass index from your height in centimetres and weight in kilograms. It shows your BMI category, the healthy weight range for your height, and an optional waist measurement check for men and women.
BMI calculator Australia
Enter your height and weight, then press calculate.
What is a healthy BMI?
Body mass index (BMI) compares your weight with your height. A BMI between 18.5 and 24.9 is the healthy weight range for most Australian adults, and this BMI calculator for Australia shows where you sit and the weight range that matches your height. It takes your height in centimetres and your weight in kilograms, so there is no need to convert units.
| BMI (adults) | Category |
|---|---|
| Under 18.5 | Underweight |
| 18.5 to 24.9 | Healthy weight range |
| 25.0 to 29.9 | Overweight |
| 30.0 and over | Obese |
Some health bodies use lower cut-offs for people of Asian and South Asian background, because health risk can rise at a lower BMI. Choose the Asian option above to see those ranges (healthy up to 22.9, higher risk from 27.5).
How to calculate BMI in kg and cm
The formula is weight in kilograms divided by height in metres squared. Worked example: a person who is 170 cm (1.70 m) and weighs 70 kg has a BMI of 70 ÷ (1.70 × 1.70) = 70 ÷ 2.89 = 24.2, which sits at the top of the healthy range. The same maths applies to the BMI calculator for women and the BMI calculator for men, because the adult categories are the same for both sexes.
BMI with age, and for teenagers
For adults, the BMI categories do not change with age, although muscle tends to fall and body fat rise in later years, so a "healthy" number can hide changes in body composition. For anyone under 18, BMI must be read against age- and sex-specific growth charts rather than the adult ranges. Ask your GP or child health nurse if you are unsure about a child or teen.
Limits of BMI, and why waist size matters
BMI does not measure body fat directly. Muscular people can have a high BMI without carrying excess fat, and some people with a normal BMI carry fat around the middle. That is why Australian guidance also uses waist circumference. Measure around your middle at the level of your belly button. Men are at increased risk at 94 cm or more and high risk at 102 cm or more. Women are at increased risk at 80 cm or more and high risk at 88 cm or more. If you want more detail, try the Navy body fat calculator.
What to do with your result
A BMI in the healthy range is a good sign, not a guarantee of health, and a BMI outside it is a prompt rather than a diagnosis. Focus on habits you can keep: regular movement, enough protein and fibre, and meals that suit your energy needs. Use the calorie calculator to estimate daily kilojoules, and the protein calculator to set a daily target. Browse weight loss and protein bar options for convenient, portion-controlled snacks.
Frequently asked questions
What is a healthy BMI for adults in Australia?
A BMI of 18.5 to 24.9 is considered the healthy weight range for most adults. Lower cut-offs may apply for people of Asian background.
Is the BMI calculator different for men and women?
No. The adult BMI categories are the same for men and women. Waist circumference thresholds do differ by sex, so this calculator uses your sex for that part.
Can I use this BMI calculator for my child or teenager?
No. Under 18s need age- and sex-specific growth charts. This calculator shows a number but not an adult category for anyone under 18.
Why is my BMI high when I lift weights?
BMI cannot tell muscle from fat. If you are very muscular, waist size and body fat percentage give a clearer picture than BMI alone.
How accurate is a BMI calculator?
BMI is a quick screening tool. It is useful across populations, but it does not measure body fat, fat distribution or fitness, so treat it as one data point.
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General information only, not medical advice. BMI is a screening tool and does not diagnose health conditions. Speak to your doctor or an accredited practising dietitian about your weight, especially if you are pregnant, an older adult or under 18.