Free BMI Calculator – Check Your Body Mass Index Instantly
Enter your height and weight to get your BMI score, your weight category and a healthy weight range for your height — calculated instantly, right in your browser.
Works in metric or imperial units · No account needed · Your numbers are never stored
Three fields, one instant result
No account, no downloads and no confusing settings — just the numbers you already know.
Add your height and weight
Switch between metric and imperial units depending on what you're used to.
We run the standard BMI formula
Your BMI is calculated using the same weight-to-height formula used by health organisations worldwide.
See your score and category
Get your BMI number, its category, and the healthy weight range for your exact height.
What Body Mass Index actually measures
Body Mass Index (BMI) is a simple screening number that compares your weight to your height. It's calculated by dividing your weight in kilograms by your height in metres squared (kg/m²) — or, in imperial units, your weight in pounds divided by your height in inches squared, multiplied by 703. The result places you into one of four widely used weight categories: underweight, normal weight, overweight, or obese.
BMI doesn't require any lab equipment or special measurements — just your height and weight — which is why it's used as a quick first indicator by doctors, fitness apps and public health bodies. It isn't a diagnosis on its own, but it's a useful starting point for understanding where your weight sits relative to general health guidelines.
| BMI Range | Category | What it generally means |
|---|---|---|
| Below 18.5 | Underweight | Weight is below the range typically considered healthy for your height. |
| 18.5 – 24.9 | Normal weight | Falls within the range generally associated with lower health risk. |
| 25.0 – 29.9 | Overweight | Above the typical range; lifestyle and activity level are worth reviewing. |
| 30.0 and above | Obese | Well above the typical range; consulting a healthcare provider is recommended. |
Where BMI falls short
BMI is a useful screening tool, but it has real limitations. It doesn't separate muscle from fat, so muscular athletes can register a higher BMI without carrying excess body fat. It also doesn't account for age, bone density, distribution of fat around the body, or differences between individuals. For older adults, pregnant women, children and very muscular people, BMI alone can be misleading.
Use your BMI result as one data point among several — alongside waist measurement, activity level and how you feel — rather than a complete picture of your health.
Built to be quick, private and accurate
Instant results
Your BMI, category and healthy weight range appear the moment you hit calculate — no page reload.
Completely free
No account, no email, no payment details — just open the page and use it.
Mobile friendly
The calculator resizes cleanly on phones and tablets, so it works wherever you check it.
Metric & imperial
Switch between kilograms/centimetres and pounds/feet-inches depending on what you're comfortable with.
Nothing is stored
Your height, weight and results stay in your browser and are never saved or shared.
Standard formula
Uses the same BMI formula referenced by major health organisations, so results are consistent and comparable.
Questions people ask about BMI
What is a healthy BMI range?
For most adults, a BMI between 18.5 and 24.9 is considered within the healthy weight range under standard classifications used by health organisations.
How is BMI calculated?
BMI equals your weight in kilograms divided by your height in metres squared (kg/m²). In imperial units, it's your weight in pounds divided by your height in inches squared, multiplied by 703.
Is BMI accurate for athletes or muscular people?
Not always. BMI can't tell muscle apart from fat, so people with high muscle mass may show a higher BMI without having excess body fat.
Does BMI differ for men and women?
The formula and category ranges are the same for adult men and women, although body composition and fat distribution naturally differ between the two.
Can I use this BMI calculator for children?
This calculator uses adult BMI categories. For children and teens, BMI is typically interpreted using age- and sex-specific growth charts, so a pediatrician is a better resource.
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