Body Mass Index (BMI) is a simple, widely-used measurement that estimates your body fat based on your height and weight. Use our BMI calculator to quickly determine your category — whether you’re underweight, healthy, overweight, or obese — and take the first step toward understanding your overall health.
BMI Calculator
Calculate your Body Mass Index and find out which weight category you fall into.
How the BMI Calculator Works
BMI is calculated using a straightforward mathematical formula:
Metric: BMI = weight(kg) ÷ height(m)²
Imperial: BMI = (weight(lbs) ÷ height(in)²) × 703
For example, a person weighing 70 kg with a height of 1.75 m has a BMI of 70 ÷ (1.75 × 1.75) = 22.9, which falls in the healthy weight range.
Worked Example — Understanding Your BMI
Scenario
James is a 34-year-old man who wants to check whether his weight is in a healthy range before starting a new fitness routine.
Inputs
- Weight: 92 kg
- Height: 178 cm
Calculation Walkthrough
- Convert height to metres: 178 cm = 1.78 m
- Square the height: 1.78 × 1.78 = 3.17
- Divide weight by squared height: 92 ÷ 3.17 = 29.0
Result
- BMI: 29.0
- Category: Overweight
Interpretation
A BMI of 29.0 falls in the Overweight range (25–29.9). This means James’s weight is higher than what is generally considered healthy for his height. For a person of his height (178 cm), a healthy weight would be roughly 59–79 kg.
Note: BMI is a screening tool, not a diagnostic. It does not account for muscle mass. If James is an athlete, his BMI may overestimate body fat. For most people, however, it is a useful starting point.
Practical Advice
Small, consistent lifestyle changes—such as a 20-minute daily walk, balanced meals, and reducing sugary or highly processed foods—can improve your BMI over time. Focus on building sustainable habits rather than aiming for rapid weight loss.
💡 Next Decision
If your BMI is above 25: Consider setting a realistic health goal for the next three months. Focus on building sustainable habits such as regular physical activity and balanced eating, then use this calculator periodically to monitor your progress.
If your BMI is below 18.5: Consider consulting a healthcare professional to check whether you are getting enough nutrition.
If your BMI is in the healthy range: Use our Calorie Calculator to estimate your daily calorie needs and create a realistic plan for maintaining, losing, or gaining weight.
Frequently Asked Questions
What is a healthy BMI range?
A BMI between 18.5 and 24.9 is considered healthy for most adults. Below 18.5 is underweight, 25–29.9 is overweight, and 30+ is obese.
Is BMI accurate for athletes?
BMI doesn’t distinguish between muscle and fat. Athletes with high muscle mass may have a high BMI while being very healthy. Use BMI as a screening tool, not a diagnostic one.
Pro Tips
- Take measurements at the same time of day for consistent results
- Use BMI alongside waist circumference for a more complete health picture
- Always consult a healthcare professional for personalized health advice