Understanding your BMI result
Body Mass Index is a simple ratio of weight to height — your weight in kilograms divided by your height in metres squared. It gives a quick, free estimate of whether your weight sits in a healthy range for your height, which is why doctors, gyms, and insurers use it as a first-pass screening number.
What the categories mean
Under 18.5 is classed as underweight, 18.5–24.9 as a healthy weight, 25–29.9 as overweight, and 30 and above as obese (split into classes I, II, and III). This calculator also shows the exact weight range that would keep you in the healthy band for your height, in both kilograms and pounds.
BMI is a guide, not a diagnosis
BMI is a useful starting point, but it has real limits. It cannot tell muscle from fat, so very muscular athletes can read as “overweight” while being extremely fit, and it does not account for bone density, age, or where you carry weight. Treat your result as one signal among many, and speak to a healthcare professional before making decisions about your health.
Metric or imperial
Switch between metric (cm and kg) and imperial (feet, inches, and pounds) with one tap — the calculator converts everything for you, so you get the same accurate BMI either way.
What is BMI and how is it calculated?
BMI (Body Mass Index) is weight in kilograms divided by height in metres squared (kg/m²). It's a quick screening tool to indicate whether someone may be underweight, normal weight, overweight, or obese.
What are the BMI categories?
Under 18.5 is underweight, 18.5–24.9 is normal weight, 25–29.9 is overweight, 30–34.9 is obese class I, 35–39.9 is obese class II, and 40+ is obese class III.
Can I use this calculator in feet, inches and pounds?
Yes — switch to Imperial mode and enter your height in feet and inches and weight in pounds. The calculator converts automatically.
Is BMI accurate for everyone?
BMI has limitations. It doesn't account for muscle mass, bone density, or fat distribution. Athletes may show as overweight despite being very healthy. Children and seniors also need different reference ranges.
What is a healthy weight for my height?
The calculator shows your personal healthy weight range (BMI 18.5–24.9) in both kg and lbs based on your height, making it easy to see your target range.
What is a good BMI for a woman?
The healthy BMI range is the same for men and women: 18.5 to 24.9. However, women naturally carry a higher percentage of body fat than men at the same BMI, which is normal and healthy. BMI does not account for this difference, which is one of its limitations.
What is the difference between overweight and obese?
A BMI of 25–29.9 is classified as overweight. A BMI of 30 or above is classified as obese, which is further divided into Class I (30–34.9), Class II (35–39.9), and Class III (40+), sometimes called severe or morbid obesity. These categories help healthcare providers assess health risk levels.
Can children use this BMI calculator?
This calculator is designed for adults aged 18 and over. BMI for children and teenagers (ages 2–19) is interpreted differently — it is compared against age- and sex-specific percentiles rather than fixed ranges. Use a dedicated paediatric BMI calculator for younger ages.