Measure your body mass index accurately and understand your health status in seconds.
Body Mass Index (BMI) is a value derived from height and weight. Enter your details to visualize your results.
* These ranges apply to adults aged 18 and above. BMI interpretation differs for children and teens.
BMI, or Body Mass Index, is a simple numerical value calculated from your height and weight. It gives you a quick snapshot of whether your body weight is within a healthy range for your height. Doctors, nutritionists, and health professionals across the world use BMI as a starting point to assess a person's overall health risk — not because it tells the full story, but because it is fast, free, and requires no special equipment.
The concept was first developed by Belgian mathematician Adolphe Quetelet in the 1830s and was later adopted by the World Health Organization (WHO) as a standard screening tool. Today it remains one of the most widely used health metrics globally, both in clinical settings and for personal health tracking.
Our BMI calculator uses the standard formulas recognized by the WHO and medical community worldwide.
Metric formula
BMI = Weight (kg) ÷ Height (m²)
Imperial / US formula
BMI = (Weight (lbs) ÷ Height (in²)) × 703
Simply enter your height and weight, choose your preferred unit system — metric (cm/kg) or US units (inches/lbs) — and hit Calculate. The result appears instantly along with a visual gauge that shows exactly where your BMI falls on the scale, from underweight through to obese.
You do not need to create an account, download an app, or share any personal data. Everything is calculated directly in your browser.
Once you receive your BMI number, here is how to interpret it using the standard WHO adult classification:
A BMI under 18.5 suggests your body weight may be too low relative to your height. This can sometimes be associated with nutritional deficiencies, weakened immunity, or other health concerns. If you consistently fall in this range, speaking with a healthcare provider is a good idea.
This is the range associated with the lowest health risk for most adults. It does not guarantee perfect health, but statistically, people in this category face a lower risk of weight-related conditions like type 2 diabetes, hypertension, and cardiovascular disease.
A BMI in this range suggests carrying somewhat more body weight than is considered ideal for your height. Lifestyle changes such as a more balanced diet and increased physical activity can often help bring BMI back into the normal range.
A BMI of 30 or higher is classified as obese. This category is further divided into Class I (30–34.9), Class II (35–39.9), and Class III (40+). Higher BMI in this range is associated with increased risk of serious health conditions including heart disease, stroke, sleep apnea, and certain cancers.
BMI is a useful screening tool, but it is not a perfect measure of health or body composition. Here are a few things it does not account for:
Muscle mass vs. fat mass
BMI only looks at total weight in relation to height. A professional athlete with dense muscle may have a high BMI but very low body fat. Conversely, someone with a normal BMI may carry a high proportion of body fat with little muscle.
Fat distribution
Where fat is stored in your body matters as much as how much you have. Abdominal or visceral fat carries higher health risks than fat stored in the hips and thighs. BMI does not distinguish between the two.
Age and sex differences
As people age, body composition naturally shifts. Women also tend to carry more body fat than men at the same BMI. These variations are not captured in the standard BMI chart.
Ethnicity
Research has shown that health risks associated with higher body fat can occur at lower BMI values in some ethnic groups, particularly South Asian populations. Some health authorities recommend adjusted BMI thresholds for these groups.
Children and teenagers
Standard adult BMI ranges do not apply to those under 18. For young people, BMI must be interpreted against age- and sex-specific growth charts.
Use this calculator as a starting point, not a final verdict. For a thorough understanding of your health, combine BMI with other assessments such as waist circumference, body fat percentage, blood pressure, cholesterol levels, and a conversation with your doctor.
Getting your BMI into a healthy range — and keeping it there — is less about willpower and more about building habits that feel sustainable month after month. No crash diets, no six-days-a-week gym schedules. Just practical shifts that compound quietly over time.
Build your meals around real ingredients
Heavily processed foods are engineered to make you eat past your hunger. When most of what you eat comes from whole sources — vegetables, pulses, eggs, fish, nuts, whole grains — your body regulates appetite far more reliably.
Shrink the package, not the pleasure
Calorie counting is exhausting. A simpler approach is to serve slightly less than you think you want, eat slowly, and check in halfway through. Your brain needs about 20 minutes to register fullness.
Move in ways you will actually repeat
The best exercise is the one you will still be doing six months from now. A daily 30-minute walk beats an intense gym routine you abandon in three weeks. Aim for 150 minutes of moderate movement per week.
Treat sleep as a health tool
When you regularly get under six hours, hunger hormones spike and fullness hormones drop. The result is stronger cravings and harder fat loss — even if your diet and exercise are solid. Target 7–9 hours nightly.
Deal with stress before it deals with your waistline
Sustained high stress keeps cortisol elevated, which encourages fat storage around the midsection. Even ten minutes of walking outside, breathwork, or journaling can meaningfully lower your baseline stress over time.
Replace liquid calories first
Sugary drinks, flavoured coffees, juices, and alcohol pack significant calories that do almost nothing to reduce hunger. Swapping these for water, plain tea, or black coffee is one of the highest-return changes you can make.
This tool is built for anyone who wants a clear, honest number — quickly, privately, and without signing up for anything.
It is particularly useful if you are starting a health or fitness goal and want an objective baseline before you begin. Having a concrete starting point makes progress measurable and keeps motivation grounded in data rather than feelings.
It is equally valuable for people who are already on a health journey and want to check in periodically. BMI alone will not tell you everything, but tracking it alongside how you feel, your energy levels, and your fitness performance gives a fuller picture of how your body is changing.
Some people use it simply before a routine health check-up — to walk in already knowing their number and have a more informed conversation with their doctor.
One clear boundary: this calculator is designed for adults aged 18 and above. BMI thresholds work differently for children and adolescents, whose healthy ranges shift with age and development stage and require age-adjusted charts to interpret correctly.
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A BMI Calculator is a tool that estimates your Body Mass Index based on your height and weight to assess whether you are underweight, normal, overweight, or obese.
BMI is calculated using the formula: BMI = weight (kg) ÷ [height (m)]². The BMI Calculator does this automatically for you.
BMI provides a general estimate of body fat, but it may not fully account for muscle mass, body composition, or age. It is a useful guideline, not a medical diagnosis.
Enter your weight and height into the calculator, select your gender if needed, and it will display your BMI along with the weight category.
A healthy BMI for most adults ranges from 18.5 to 24.9. This range indicates normal weight relative to height.
Yes, BMI can change as you age due to changes in muscle mass and body composition, but the standard BMI ranges are generally used for adults.
For adult females, a normal BMI typically ranges from 18.5 to 24.9, similar to males, though body composition may vary.
BMI is calculated by dividing a person’s weight in kilograms by the square of their height in meters: BMI = weight ÷ height².
Your BMI depends on your height. For example, a person weighing 70 kg and 1.75 m tall has a BMI of 22.9, which is considered normal.
BMI for age is used for children and teens to assess growth patterns. Adults generally use standard BMI ranges regardless of age.
* While this tool can point you in a useful direction, it is not a clinical assessment. If your result concerns you, or if you have an existing health condition, the right next step is a conversation with a qualified medical professional.