Check your Body Mass Index from your height and weight, in metric or imperial units. The result shows your BMI, its category, and the healthy weight range for your height.
BMI Calculator
How the BMI Calculator Works
Body Mass Index (BMI) is a quick screening number that compares your weight with your height to give a rough idea of whether your weight sits in a range linked with lower health risk. Doctors, insurers and fitness apps use it as a first check because it needs nothing more than a scale and a tape measure. It is most useful as a starting point: a result outside the healthy range is a prompt to look closer, while a result inside it is one encouraging sign among many.
The formula is simple. BMI equals your weight in kilograms divided by your height in metres squared: BMI = kg ÷ m². If you think in pounds and inches, the same idea applies after converting to metric, which this calculator does for you automatically when you choose imperial units. Only two inputs matter — your current weight and your height without shoes — so small measuring errors can nudge the result, especially for shorter adults where a centimetre or two changes the squared height noticeably.
This calculator shows your BMI rounded to two decimal places, names the standard category it falls into, and works out the healthy weight range for your height. The categories are the widely used adult bands: under 18.5 is underweight, 18.5 to 24.9 is the healthy weight range, 25 to 29.9 is overweight, and 30 or above is obese. The healthy weight range shown is simply the weights at which someone of your height would score between 18.5 and 24.9.
How to Use This Calculator
- Weigh yourself, ideally in the morning before breakfast, and note the result.
- Measure your height standing straight against a wall, without shoes.
- Choose metric (kilograms and centimetres) or imperial (pounds and inches) in the calculator above.
- Enter your weight and height, then press Calculate.
- Read your BMI, its category, and the healthy weight range for your height — then compare over time rather than day to day, because normal water and food shifts can move your weight by a kilogram or more.
Example
If you weigh 70 kg and are 175 cm tall, your BMI is 70 ÷ 1.75² = 22.86, which falls in the Healthy weight category. For that height, the healthy weight range works out to roughly 56.7 kg to 76.3 kg.
A second example: at 60 kg and 165 cm, BMI is 60 ÷ 1.65² = 22.04 — also healthy weight, with a healthy range for that height of about 50.4 kg to 67.8 kg. Notice how the healthy range is wide: there is no single “perfect” weight for a given height, just a band.
Understanding Your Result
The four adult categories are screening bands, not diagnoses. Underweight (below 18.5) can be linked with nutritional gaps or other health issues worth checking. The healthy range (18.5–24.9) is where population studies find the lowest average risk for most adults. Overweight (25–29.9) and obese (30 and above) ranges are associated with gradually higher average risk of conditions such as type 2 diabetes and heart disease across large groups of people.
BMI has well-known limits. It cannot tell muscle from fat, so a strength athlete with a lot of muscle may score “overweight” while carrying little body fat. It does not show where fat is stored, even though waist fat carries more risk than hip fat. It can also mislead for older adults, who naturally lose muscle, and the standard bands were not designed for children or for pregnancy. Treat your number as a general guide and a conversation starter — if it surprises or worries you, a healthcare professional can assess your health properly with measurements BMI cannot make.
A useful companion check is waist circumference, which says something BMI cannot: where your weight sits. As a rough guide, risk rises when a man’s waist exceeds about 94 cm (37 inches) and a woman’s exceeds about 80 cm (31.5 inches), whatever the BMI says. Someone in the healthy BMI band with a large waist may still carry extra risk, while someone just over BMI 25 with a modest waist and good fitness may be healthier than the label suggests. Looking at both numbers together — BMI for overall size, waist for fat distribution — gives a fairer picture than either one alone, and both take under a minute to measure at home.
BMI Calculator FAQs
What is a healthy BMI for adults?
For most adults, a BMI between 18.5 and 24.9 is considered the healthy range. It is a population guideline, not a personal target, and your own healthy weight also depends on muscle, build, age and overall health.
Is BMI accurate for athletes and bodybuilders?
Often not. Muscle is denser than fat, so a very muscular person can score in the overweight range with low body fat. Waist measurement or a body fat estimate gives a fuller picture for athletes.
Does BMI work for children?
No — children and teenagers need age- and sex-specific BMI percentiles, because their bodies are still growing. This calculator uses the adult bands, so it is intended for adults only.
How often should I check my BMI?
Once every few weeks or months is plenty if you are tracking a change. Daily weighing mostly measures water shifts, and slow trends are far more meaningful than single readings.
Can my BMI be healthy but my health still be at risk?
Yes. BMI says nothing about blood pressure, cholesterol, blood sugar, smoking or fitness. A healthy BMI is one positive sign, not a clean bill of health — regular check-ups still matter.
Related calculators: Calorie Calculator, Age Calculator, Percentage Calculator.