BMI Calculator

This BMI calculator gives you a quick Body Mass Index reading from just your height and weight, and — crucially for Indian users — lets you read that number against the ICMR / WHO Asia-Pacific cutoffs as well as the international WHO standard. BMI is a screening number, not a body-fat measurement, but across large populations it correlates strongly with cardiovascular and metabolic risk, which is why doctors, insurers, and fitness professionals worldwide still use it as the first checkpoint in a weight-related health review.

It is useful for almost anyone keeping an eye on their weight: someone starting a fitness plan, a person whose doctor mentioned their weight at a check-up, a parent tracking their own health, or simply anyone curious where they sit relative to a healthy range. Because it needs only two inputs that you already know, it takes seconds and gives an immediate, easy-to-act-on category.

The formula

BMI is your weight divided by the square of your height.

Metric: BMI = weight (kg) / height (m)2

Imperial: BMI = (weight (lb) / height (in)2) x 703

Two scales, two sets of thresholds

The WHO standard scale — healthy 18.5–24.9, overweight at BMI 25, obese at 30 — is used globally for the general population. The WHO Asia-Pacific scale, adopted by the ICMR for Indian clinical guidelines, applies lower cutoffs: healthy 18.5–22.9, overweight 23.0–24.9, and obese at 25 and above. These lower thresholds exist because research found that South-Asian populations carry roughly 3–5% more body fat at the same BMI as Europeans, with diabetes, high blood pressure, and heart disease appearing at lower BMI values. If you are of Indian or wider South-Asian descent, the Asia-Pacific scale is the more clinically relevant one to read.

Worked example

Consider an adult weighing 70 kg at a height of 170 cm. First convert height to metres: 170 cm = 1.70 m. Then BMI = 70 ÷ (1.70 × 1.70) = 70 ÷ 2.89 = 24.2. On the international WHO scale this sits in the normal range, but on the ICMR / Asia-Pacific scale a BMI of 24.2 falls into the overweight band — a clear illustration of why the scale you choose matters for Indian users. The same number, two different readings.

Your healthy weight range

Alongside the BMI number, this tool works backwards from the healthy band to show the weight range that would keep you in it at your current height. On the ICMR scale that band is BMI 18.5 to 22.9; on the WHO standard scale it is 18.5 to 24.9. Seeing the actual kilogram (or pound) range is often more motivating than the index itself, because it turns an abstract number into a concrete target. As your height does not change, only the weight figure moves — so it doubles as a simple goal to track over weeks and months.

How to read your result, and tips

Use your category as a prompt, not a verdict. If you fall above the healthy range on the ICMR scale, it is a gentle flag to review diet, activity, and routine — small, steady changes work better than crash dieting. If you are below 18.5, that underweight reading is worth attention too, as it can signal undernutrition. Pairing BMI with your waist measurement gives a much better picture of health risk, because where you carry weight matters as much as how much.

Limitations and common mistakes

BMI cannot tell muscle from fat. Athletes, bodybuilders, and manual labourers with high muscle mass often read as overweight despite being lean, while some older adults with low muscle and high fat read as normal. It is also not designed for children, pregnant women, or the frail elderly. Common mistakes include entering height in centimetres where metres are expected, using the wrong scale for your ethnicity, and treating a single reading as the whole story. Body-fat percentage, waist circumference, and waist-to-hip ratio together give a fuller clinical picture.

This is a health screening tool, not a diagnosis. A BMI in any band does not by itself confirm or rule out a health problem. For any decision about your weight or health, consult a doctor, who can weigh BMI alongside your waist measurement, blood markers, family history, and overall lifestyle.