BMI Calculator
Calculate your body mass index from height and weight in either metric or imperial units, with live results showing your weight category and health advice.
FreeOnline Tool
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How to Use
- Choose a unit system: metric (centimeters and kilograms) or imperial (inches and pounds)
- Enter your height and weight, and the BMI value is calculated live as you type
- The result area shows the BMI number, the weight category (underweight, normal, overweight or obese) and matching health advice
- A color-coded progress bar shows where your BMI falls within the standard ranges
Features
- Live calculation: the BMI value and category appear as soon as height and weight are entered
- Two unit systems: switch freely between metric (cm/kg) and imperial (in/lb)
- Visual scale: a color-coded BMI range bar shows where your result sits
- Health advice: tailored guidance based on the BMI category
- Chinese national standard: uses the classification commonly applied in China (underweight below 18.5, normal 18.5-24, overweight 24-28, obese 28 and above)
Use Cases
Routine health tracking
Calculate your BMI regularly to follow weight changes and keep an eye on your overall condition.
Fitness progress tracking
Compare BMI before and after a training period to gauge fat loss or muscle gain results.
Weight management planning
Use the BMI category and accompanying advice to build a sensible weight management plan.
Health check-up reference
Use BMI as a standard reference figure alongside a routine physical to see whether your build sits in the healthy range.
FAQ
What is the BMI formula?
Metric: BMI = weight in kilograms divided by height in meters squared. Imperial: BMI = weight in pounds divided by height in inches squared, multiplied by 703.
Which classification thresholds are used?
The Chinese national standard: underweight below 18.5, normal 18.5 to 24, overweight 24 to 28, and obese at 28 and above.
Does BMI fully reflect how healthy I am?
BMI is a widely used reference figure, but it does not suit athletes with high muscle mass or older adults who have lost muscle. Combine it with measures such as body fat percentage for a fuller picture.
Can children use this calculator?
This tool is intended for adults. Assessing BMI for children and adolescents requires age- and sex-specific percentile curves, so please use a dedicated pediatric BMI tool instead.