BMI Calculator
Calculate your Body Mass Index (BMI) and find out which weight category you fall into based on your height and weight.
Disclaimer
This calculator provides estimates for general information purposes only. Results are based on standard formulas and may not reflect your individual circumstances. Always consult a qualified professional for advice specific to your situation.
Frequently Asked Questions
What is a healthy BMI range?
Is BMI accurate for everyone?
What is BMI?
Body Mass Index (BMI) is a simple measure that uses your height and weight to estimate whether you are underweight, normal weight, overweight, or obese.
How this calculator works
BMI is calculated as weight (kg) divided by height (m) squared. This calculator supports both metric (cm/kg) and imperial (inches/lbs) units, converting automatically. The visual scale shows where your BMI falls across the spectrum from underweight (<18.5) to obese (30+), and the healthy weight range tells you the weight range that corresponds to a BMI of 18.5-25 for your height. Note: BMI is a screening tool, not a diagnostic — it doesn't account for muscle mass or body composition.
WHO BMI Categories
World Health Organization classifies: Underweight <18.5, Normal 18.5-24.9, Overweight 25-29.9, Obese class I 30-34.9, class II 35-39.9, class III ≥40. These categories are used by Australian Department of Health and most medical guidelines. The Australian Bureau of Statistics 2023 data: 67% of adults are overweight or obese (BMI ≥25).
BMI Limitations
BMI doesn't distinguish muscle from fat. Athletes/bodybuilders often have BMI >30 with low body fat. Elderly often have BMI in 'normal' range but low muscle (sarcopenia) + high body fat. Asian populations have higher health risks at lower BMI — Asian-specific cutoffs: overweight ≥23, obese ≥27.5. Pregnant/lactating women: BMI not applicable.
Better Metrics to Combine
Waist circumference: men ≥94cm (102cm = high risk), women ≥80cm (88cm = high risk). Waist-to-height ratio: should be <0.5. Body fat percentage: men 10-25%, women 18-32% (typical healthy ranges). Use BMI + waist + body fat for a fuller picture rather than relying on BMI alone.
Health Implications
BMI ≥30 is associated with higher risk of type 2 diabetes, cardiovascular disease, several cancers, sleep apnoea, osteoarthritis, and depression. BMI <18.5 is associated with osteoporosis, fertility issues, and reduced immunity. The 'overweight' category (25-29.9) has mixed evidence — some research suggests slight overweight may not increase mortality in older adults.
Official Sources
All calculations are performed in your browser — your data never leaves your device. Results are for general guidance only and should not be considered professional financial advice.
Built and maintained by Konstantin Iakovlev. Data sourced from the ATO and official Australian government sources.