BMI Calculator – Check Your Body Mass Index Online

For Sri Lankans and other South Asians, a BMI between 18.5 and 22.9 is considered normal. A BMI of 23.0–24.9 is overweight, 25.0–29.9 is Obesity Class I, 30.0–39.9 is Obesity Class II, and ≥ 40 is Obesity Class III. These thresholds are lower than international WHO standards because South Asians tend to develop metabolic complications at lower BMI values.

Research shows that South Asians (including Sri Lankans) develop obesity-related health complications — such as type 2 diabetes and cardiovascular disease — at lower BMI values compared to Western populations. This is partly due to body composition differences: South Asians tend to carry a higher proportion of body fat at the same BMI. Lower cut-off values are therefore recommended for this population.

BMI = Weight (kg) ÷ Height (m)². For example, if you weigh 70 kg and are 1.68 m tall: BMI = 70 ÷ (1.68 × 1.68) = 70 ÷ 2.8224 ≈ 24.8. This calculator performs all unit conversions and the calculation for you automatically.

BMI is a useful population-level screening tool but has limitations. It does not measure body fat percentage, muscle mass, or fat distribution. It can be misleading for athletes (who have more muscle), elderly people (who may have lost muscle mass), and pregnant women. Your doctor may also consider waist circumference, blood pressure, blood sugar, and cholesterol for a more complete assessment.

You should seek medical assessment if your weight changes suddenly or unintentionally, if you have symptoms related to obesity, if you experience fatigue or breathlessness, if you have been diagnosed with diabetes or hypertension, or if daily activities are becoming difficult. Early intervention can significantly reduce long-term complications and improve quality of life.

Yes. Athletes and highly muscular individuals may have a high BMI without excess body fat, because muscle is denser than fat. In such cases BMI can overestimate health risk. This is one of the well-known limitations of BMI as a screening tool — which is why doctors also consider body composition, waist circumference, and metabolic markers.

Yes. Abdominal fat (fat stored around the abdomen) increases metabolic risk even in people with a normal BMI. Excess waist circumference is linked to higher risk of type 2 diabetes, heart disease, and high blood pressure. Doctors may measure waist circumference alongside BMI for a more complete health picture.

Higher BMI is associated with increased risk of type 2 diabetes, particularly in South Asians who develop metabolic complications at lower BMI values. However, BMI alone cannot diagnose or predict diabetes — blood sugar testing (such as FBS or HbA1c) is required for that. If your BMI is in the overweight or obesity range, your doctor may recommend screening for diabetes.