BMI Calculator
Calculate your Body Mass Index
Track your BMI over time with Progress
What is BMI?
BMI (Body Mass Index) is a simple calculation that compares your height and weight. It's often used as a general screening tool to spot potential health risks at a population level.
But BMI doesn't tell the whole story. That's why it works best as one piece of information, alongside things like body measurements, health markers, and how you feel.
Track your BMI and more with Progress.
We believe progress is personal, not one number
Tracking your BMI over time gives you a clearer picture of your health journey. It shows not just where you are today but how far you've come.
It helps you spot trends, understand what's working, and make small sustainable changes that add up. It's not about chasing a perfect number. It's a simple way to stay motivated, focused, and in control whatever your body goal is.
Learn more:
BMI Chart: Categories and Health Ranges
These are the standard BMI categories used by the NHS and WHO. They apply to adults aged 18 and over.
| Category | BMI Range | What It Means |
|---|---|---|
| Underweight | Below 18.5 | Your body might need a bit more fuel and nourishment |
| Healthy weight | 18.5 – 24.9 | A range linked to the lowest health risks |
| Overweight | 25 – 29.9 | Worth keeping an eye on, especially alongside other metrics |
| Obese | 30 and above | A starting point, not a label. Small changes can make a big difference |
BMI is a screening tool, not a diagnosis. It doesn't distinguish between muscle and fat, and it doesn't account for where your body stores fat. For a fuller picture, consider tracking additional metrics alongside BMI.
Frequently Asked Questions
What is a healthy BMI?
A healthy BMI falls between 18.5 and 24.9. This range is linked to the lowest risk of weight-related health problems for most adults. That said, BMI doesn't account for muscle mass, bone density, age, or sex, so it's best used alongside other measurements.
How is BMI calculated?
You divide your weight in kilograms by your height in metres squared. The formula is: BMI = weight (kg) / height (m)². So if you weigh 70 kg and you're 1.75 m tall, your BMI would be 22.9.
What are the BMI categories?
There are four main categories: Underweight (below 18.5), Healthy weight (18.5 to 24.9), Overweight (25 to 29.9), and Obese (30 and above). Some health organisations break these down further into subcategories.
What are the limitations of BMI?
BMI doesn't distinguish between muscle and fat, so muscular people can be classified as overweight despite being healthy. It also doesn't account for fat distribution, age, sex, or ethnicity. That's why it works best as one metric among many, alongside body measurements, body fat percentage, and how you feel.
How often should I check my BMI?
Once a month is a good starting point. What matters most is tracking the trend over time, not any single reading. Progress can log your BMI automatically and show you how it changes alongside your other body measurements.
Track your BMI over time with Progress