How to Calculate Your BMI (2026)
You can calculate your Body Mass Index with our BMI Calculator. Enter your height and weight in metric or imperial units, and the tool shows your BMI value and weight category instantly. Your health data never leaves your device.
What Is BMI?
BMI is a simple screening number based on your weight and height. It helps identify whether you are underweight, normal weight, overweight, or obese according to standard ranges. It is not a direct measure of body fat, but it is a useful starting point for health conversations.
The formula is kg/m² in metric units, or 703 × pounds ÷ inches² in imperial units. Our BMI Calculator applies the right formula automatically.
How to Use Our BMI Calculator
- Open the BMI Calculator.
- Choose metric (kg/cm) or imperial (lb/ft-in) units.
- Enter your weight and height.
- Read your BMI and weight category.
- Copy or download the result if you want to save it.
BMI Categories
| Category | BMI Range |
|---|---|
| Underweight | Below 18.5 |
| Normal weight | 18.5 – 24.9 |
| Overweight | 25.0 – 29.9 |
| Obese | 30.0 and above |
What BMI Doesn’t Capture
BMI is just weight ÷ height², so it can’t see what your weight is made of or where it sits:
- Muscle vs fat — a muscular athlete can read “overweight” on BMI while carrying very low body fat.
- Fat distribution — abdominal fat is a bigger health risk than fat on the hips, but BMI weighs them the same. Pairing it with a waist measurement adds that context.
- Age — older adults lose muscle, so a “normal” BMI can sit on top of low muscle mass.
- Population differences — some health bodies use a lower overweight threshold (around 23) for people of South and East Asian descent, where risk rises at a lower BMI.
Treat BMI as a fast first screen that tells you whether a closer look is worth taking — not a verdict on your health.
Common Use Cases
- Health checkups — get a quick screening number.
- Fitness goals — track changes over time.
- Medical forms — provide BMI when requested.
- Weight management — understand where you fall on the chart.
FAQ
How is BMI calculated?
BMI equals weight in kilograms divided by height in meters squared. In imperial units, the formula is 703 × pounds ÷ inches².
What is a healthy BMI range?
For most adults, a BMI between 18.5 and 24.9 is considered normal. Below 18.5 is underweight, 25 to 29.9 is overweight, and 30 or above is obese.
Is BMI accurate for everyone?
BMI is a useful screening tool but not a diagnosis. It can overestimate body fat in muscular people and underestimate it in older adults with less muscle.
Does this calculator work for children?
No. This calculator uses adult BMI categories. Children and teens need age- and sex-specific percentile charts.
Should I measure my waist too?
It helps. BMI ignores where fat sits, and abdominal fat carries more health risk, so many clinicians pair BMI with waist circumference for a fuller picture. BMI is the quick screen; waist adds the context it misses.
What related health tools are available?
For daily calorie targets, try our Calorie Calculator. For weight conversions, use our Weight Converter.
Want your screening number in the units you actually use? The BMI Calculator takes kg/cm or lb/ft-in and shows your category instantly — and if you’re acting on the result, pair it with the Calorie Calculator to set a daily target.