This BMI calculator computes your Body Mass Index from your height and weight using the standard WHO formula. It displays your BMI value along with the corresponding weight category such as underweight, normal, overweight or obese. The calculation is performed entirely in your browser, so your personal health data never leaves your device. Use this tool for a quick health assessment anytime.
Enter your values to see the result.
Height: 175 cm, Weight: 70 kg → BMI: 22.9 – Normal weight
A height of 175 cm and weight of 70 kg gives a BMI within the healthy range.
Height: 5'9", Weight: 180 lbs → BMI: 26.6 – Overweight
Imperial units are converted automatically before the calculation.
Height: 160 cm, Weight: 50 kg → BMI: 19.5 – Normal weight
A lighter person with a shorter height still falls in the normal range.
Body Mass Index, commonly known as BMI, is one of the most widely used screening tools for assessing whether a person has a healthy body weight relative to their height. It was developed in the 1830s by the Belgian polymath Adolphe Quetelet and has since become a standard metric in public health, clinical practice and fitness assessment worldwide. The calculation is straightforward: your weight in kilograms divided by the square of your height in meters.
Despite its simplicity, BMI provides a reasonable estimate of body fatness for most people and correlates well with more direct measures of body composition such as underwater weighing and dual-energy X-ray absorptiometry. Health organizations including the World Health Organization use BMI categories to define population-level weight status thresholds and track obesity trends across countries and demographics over time.
This BMI calculator takes two inputs: your height and your weight. You can enter measurements in either metric units (centimeters and kilograms) or imperial units (inches and pounds). When imperial units are used, the tool automatically converts them to metric before applying the standard BMI formula. The conversion uses the exact ratios of 2.54 centimeters per inch and 0.453592 kilograms per pound to ensure accuracy.
Once both values are provided, the calculator computes the BMI and displays it alongside the corresponding WHO classification. The categories range from underweight (below 18.5) through normal weight (18.5 to 24.9), overweight (25.0 to 29.9) and obese (30.0 and above). The result appears instantly with no page reload, making it easy to experiment with different values and see how changes in weight affect your BMI category.
The WHO classification system divides BMI into four main categories that serve as general guidelines for weight status. A BMI below 18.5 indicates underweight, which may suggest malnutrition or an underlying health condition. The normal weight range of 18.5 to 24.9 is associated with the lowest risk of weight-related health problems for most adults. Overweight, ranging from 25.0 to 29.9, signals an increased risk of conditions such as cardiovascular disease, type 2 diabetes and certain cancers. Obesity, defined as a BMI of 30.0 or higher, carries a significantly elevated risk for these and other chronic conditions.
It is important to remember that BMI is a screening tool, not a diagnostic one. It does not measure body fat directly and cannot distinguish between fat mass and muscle mass. An athlete with significant muscle development may have a BMI in the overweight range while having very low body fat. Similarly, an older adult with reduced muscle mass may have a normal BMI while carrying excess fat. For these reasons, BMI should always be interpreted in context with other health indicators and professional medical advice.
All calculations happen locally in your browser. Your height, weight and BMI results are never sent to any server, stored in any database, or shared with any third party. The tool uses standard JavaScript arithmetic to compute the result instantly, so there is no network dependency and no loading time. You can use it offline and with complete confidence that your personal health data stays on your device.
The formula used by this calculator follows the exact WHO standard and produces the same results you would get from any clinical BMI calculator. However, this tool is intended for informational purposes only and should not replace professional medical advice. If you have concerns about your weight or health, consult a qualified healthcare provider who can evaluate your complete health profile including body composition, blood work, family history and lifestyle factors.
BMI stands for Body Mass Index and is a numerical value calculated by dividing your weight in kilograms by the square of your height in meters. The formula is BMI = weight (kg) / height² (m²). It provides a simple screening tool to categorize individuals into weight classes such as underweight, normal weight, overweight and obese. While BMI does not directly measure body fat, it correlates well with more direct measures and is widely used by health professionals around the world for initial assessments.
The World Health Organization defines four main BMI categories. A BMI below 18.5 is classified as underweight. A BMI between 18.5 and 24.9 is considered normal or healthy weight. A BMI between 25.0 and 29.9 indicates overweight. A BMI of 30.0 or above is classified as obese. These ranges apply to adult men and women of all ages and are used globally as a standard reference for weight status screening and public health research purposes.
BMI is a useful screening tool but has limitations. It does not distinguish between muscle mass and fat mass, so athletes or very muscular individuals may have a high BMI despite being healthy. It also does not account for age, sex, bone density or ethnic differences in body composition. For a comprehensive health assessment, BMI should be considered alongside other measurements such as waist circumference, body fat percentage, blood pressure and cholesterol levels. Always consult a healthcare professional for a complete evaluation of your health status.
Yes, this calculator supports both metric and imperial units. You can enter your height in centimeters or inches and your weight in kilograms or pounds. The tool automatically converts imperial units to metric before performing the BMI calculation using the standard WHO formula. This means you get the same accurate result regardless of which unit system you choose to enter your measurements in, making the tool convenient for users from any country or region.
No, all calculations are performed entirely in your browser using JavaScript. Your height, weight and BMI results are never transmitted over the network, stored in any database, or processed by any third party. You can use this tool with complete confidence that your personal health information remains private and stays on your device at all times. No cookies, tracking or data collection is involved in the operation of this calculator.
Last updated on 2026-09-26 · Written by UtiliaTools