BMI Calculator

Written byOleh Soloninupdated 27 September 2026

Weight kg

Height cm

Result

BMI22.7
CategoryHealthy weight
Healthy weight for your height58.7–79.2 kg
Distance to the healthy rangewithin the healthy range

This result is informational only and is not professional advice.

A population statistic applied to one person

Calculate body mass index from height and weight, with the WHO categories and an honest explanation of where BMI stops being useful.

BMI is weight divided by height squared. It was designed in the 1830s to describe populations, and it does that job well — it was never intended to assess an individual.

The formula cannot distinguish muscle from fat, or where fat sits. A muscular athlete and someone carrying excess weight can share a BMI of 27 while being in entirely different health situations.

How to use

Enter your weight in kilograms and your height in centimetres.
The result gives your BMI to one decimal place and its WHO category, including the obesity classes.
Below it you see the healthy weight range for your height and how many kilograms separate you from it.

One scale for women and men

Body mass index is weight in kilograms divided by the square of height in metres: 72 kg at 1.78 m gives 72 ÷ 1.78² = 22.7. The WHO adult scale is the same for women and men and does not change with age; there are no separate female and male BMI norms.

The sexes differ in body composition instead: at the same BMI women carry on average a larger share of fat and men of muscle. That is why BMI is paired with waist size — by WHO criteria, risk rises above 80 cm for women and 94 cm for men.

WHO classification for adults over 18. The notation 18.5–24.9 means a BMI of at least 18.5 and below 25; the weights come from the calculator on this page.
WHO category	BMI	Weight at 170 cm
Underweight	under 18.5	under 53.5 kg
Healthy weight	18.5–24.9	53.5–72.2 kg
Overweight	25–29.9	72.3–86.6 kg
Obesity class I	30–34.9	86.7–101.1 kg
Obesity class II	35–39.9	101.2–115.5 kg
Obesity class III	40 and over	from 115.6 kg

The healthy weight for your height

The healthy band is a BMI of at least 18.5 and below 25 — WHO writes it as 18.5–24.9, to one decimal place. Multiply 18.5 and 25 by your height in metres squared to turn it into kilograms; the upper limit itself already counts as overweight. The calculator does this for whatever height you enter.

The last column shows how the same weight reads at different heights: 70 kg is obesity class I at 150 cm, healthy from 170 to 190 cm, and underweight at 195 cm.

These limits do not apply to children and teenagers, whose BMI is read against WHO percentiles for age and sex.

Every row comes from the calculator on this page.
Height, cm	Healthy weight, kg	BMI at 70 kg
150	41.7–56.2	31.1
155	44.5–60	29.1
160	47.4–63.9	27.3
165	50.4–68	25.7
170	53.5–72.2	24.2
175	56.7–76.5	22.9
180	60–80.9	21.6
185	63.4–85.5	20.5
190	66.8–90.2	19.4
195	70.4–95	18.4

What this calculator shows

Your BMI value and its WHO category
The weight range that would place you in the healthy band
The healthy weight range for your height and how far you are from it

What to keep in mind

WHO categories: under 18.5 underweight, 18.5–24.9 healthy, 25–29.9 overweight, 30–34.9 obesity class I, 35–39.9 class II, 40 and over class III.
These cut-offs were derived from European populations; risk thresholds are lower for South and East Asian groups.

Where the numbers come from

Checked against the WHO body-mass-index classification.

FAQs

What is a healthy BMI?

18.5 to 24.9 by WHO criteria, the same for women and men. To judge the risk that comes from where fat sits, add waist circumference or waist-to-height ratio.

What is a healthy weight for 170 cm?

53.5 to 72.2 kg. At 160 cm it is 47.4 to 63.9 kg; at 180 cm, 60 to 80.9 kg.

How much do I need to lose to reach a healthy BMI?

The last line of the result says so. At 175 cm and 90 kg, for example, BMI is 29.4 and the healthy range ends at 76.5 kg — 13.5 kg away.

Is BMI accurate for athletes?

With caveats. Muscle is denser than fat, so a heavily muscled person can register as overweight while carrying little fat. For them a body fat estimate from tape measurements says more.

Why does BMI use height squared?

It was an empirical fit for adult populations. Bodies do not scale in two dimensions, so BMI reads high for very tall people and low for very short ones with the same proportions.

Does BMI apply to children?

Not directly. Children are assessed on WHO percentile charts for age and sex, because body composition changes constantly during growth.

Worked example

A worked case

Input: 180 cm, 81 kg

Output: BMI 25.0

Note: That lands one decimal into 'overweight'. For a lean, muscular person it may mean nothing at all — which is precisely the limitation of the measure.

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