Free BMI calculator
Your BMI, and the weight range it points to.
Two numbers in, and you get your body mass index, the band it falls in, and — the part most BMI calculators leave out — the actual weight range that would put your height inside the healthy band. It runs in your browser: no account, no email, nothing sent anywhere.
General wellness guidance, not medical advice. If you are pregnant, breastfeeding, under 18, or managing a medical condition, talk to a doctor or a registered dietitian before acting on any of these numbers.
How BMI is worked out
Weight in kilograms divided by height in metres squared — kg ÷ m². That is the
entire formula. In imperial it is 703 × lb ÷ in², which is the same thing
wearing a different hat. Nothing else goes in: not age, not sex, not muscle, not where the
weight sits on you.
| BMI | Band | What it means, honestly |
|---|---|---|
| Under 18.5 | Underweight | Worth investigating, particularly if it was not deliberate |
| 18.5 – 24.9 | Healthy weight | The band population data associates with the lowest risk |
| 25.0 – 29.9 | Overweight | A prompt to look at waist and trend, not a diagnosis |
| 30.0 and above | Obesity | Worth a conversation with a doctor, with real measurements |
What BMI is genuinely bad at
It cannot tell muscle from fat, so trained people read high. It ignores fat distribution, so two people with identical BMI and very different abdominal fat get identical labels. It was built on European population data, and the risk thresholds sit lower for South and East Asian populations — 23 and 27.5 rather than 25 and 30. And it says nothing about direction: a stable 26 and a 26 on the way up from 22 are not the same situation at all.
So use it the way a screening tool is meant to be used. If the number is inside the band and your waist is under half your height, there is nothing here worth acting on. If it is outside, the useful next step is a tape measure and a few weeks of honest tracking, not a stricter calculator.
If you want to change the number
Moving BMI means moving weight, and moving weight means a calorie balance held for long enough to matter. The deficit calculator sizes that for you and gives a realistic date; the calorie calculator gives the daily target; the protein calculator covers the part that decides how much of the loss is fat rather than muscle. NutriLog AI then tracks the weight trend against the target so you can see which way it is actually going, rather than re-typing your weight into a calculator every fortnight.
Common questions
What is a healthy BMI?
By the WHO cut-points used worldwide, 18.5 to 24.9 is the healthy band, under 18.5 is underweight, 25 to 29.9 is overweight and 30 or above is obesity. Those numbers came from population mortality data, which is exactly what they are good for: describing risk across a large group. They say much less about any one person standing in front of you.
Is BMI accurate for muscular people?
No, and this is its best-known failure. BMI is weight divided by height squared; it has no way to tell muscle from fat. A lean, heavily trained person routinely reads as "overweight" and occasionally as "obese" while carrying single-digit body fat. If you lift seriously, use waist measurement and how your clothes fit instead, and ignore the label BMI hands you.
Are the BMI cut-points different for Indian and other Asian populations?
Yes. The WHO published lower Asian cut-points because cardiometabolic risk — type 2 diabetes in particular — appears at a lower BMI in South and East Asian populations: 23 rather than 25 for overweight, and 27.5 rather than 30 for obesity. This calculator shows the standard international bands. If those lower thresholds apply to you, read your result against 23 and 27.5 instead.
What should I use instead of BMI?
Waist circumference is the single most useful addition and needs nothing but a tape measure — it tracks abdominal fat, which is the part most strongly tied to metabolic risk. Waist-to-height ratio, kept under 0.5, is a good rule of thumb. Beyond that: your weight trend over months rather than a single reading, blood pressure, and a lipid and glucose panel from an actual blood test.
Does BMI matter if my weight is stable?
It matters less than the trend. A stable weight inside the healthy band with a decent diet and some training is a better position than a "perfect" BMI reached by crash dieting and lost again. What changes outcomes is the direction you are moving in and how long you hold it — which is a tracking question, not a calculator question.
Is this BMI calculator free, and is my data stored?
Free, and nothing is stored. The arithmetic runs in your browser: no account, no email, nothing sent to a server, so there is nothing for us to keep.
Other free calculators
A number is a snapshot. A trend is the truth.
NutriLog AI logs your weight, smooths the daily noise into a trend line and projects a realistic goal date from it. Free, no ads, Android. Free on Google Play.