# BMI calculator

Source: https://nume.co.in/tools/bmi-calculator/ · Checked on 12 November 2026

Enter your height and weight. You get your body mass index (BMI), its category in the World Health Organization's classification for adults, and the weight range WHO calls normal for your height.

## What the number means

BMI compares your weight with your height. WHO groups adults like this:

| BMI | WHO adult category |
|---|---|
| Under 18.5 | Underweight |
| 18.5 to 24.9 | Normal weight |
| 25.0 to 29.9 | Overweight |
| 30.0 and over | Obesity |

The categories are for adults. For children and teenagers, WHO compares BMI with the usual range for their age.

BMI can't tell muscle from fat, so someone with a lot of muscle can come out as overweight.

For many Asian populations, a WHO expert consultation found that the risk of type 2 diabetes and heart disease rises at BMIs under 25, and it named 23 and 27.5 as further points for public health action.

## How it is worked out

BMI is your weight in kilograms divided by your height in metres, squared. For 70 kg and 1.75 m, that is 70 ÷ (1.75 × 1.75) = 22.9. The calculator rounds BMI to one decimal and takes the category from that rounded figure.

The normal range for a height runs from 18.5 × height² to 24.9 × height², shown in whole kilograms inside that range. For 1.75 m it is 56.7 to 76.3 kg, shown as 57 to 76 kg.

Pounds are converted at 0.45359237 kg each and inches at 2.54 cm, and both are held to one decimal. Heights from 100 to 250 cm and weights from 25 to 400 kg are accepted.

**In Nume:** set-up asks your height and weight, and your plan follows your latest weigh-in. Nume won't plan very low-calorie days or a target weight below a healthy range for your height.

## Ask an assistant

ChatGPT, Claude, Gemini, Perplexity and other assistants can run this calculator from a link and read the answer as text. Ask one to open this link with your own numbers:

`https://nume.co.in/tools/bmi-calculator/answer?height_cm=170&weight_kg=72`

Height can also be `height_ft` and `height_in`, and weight `weight_lb`. [The link on its own](/tools/bmi-calculator/answer) lists every input.

Apps that take an MCP server, such as Claude and Cursor, can add all four calculators at once: [see Tools](/tools/#use-them-in-chatgpt-claude-and-other-assistants).

## Sources

- [WHO: Malnutrition in women, BMI definitions and cut-offs (Nutrition Landscape Information System)](https://www.who.int/data/nutrition/nlis/info/malnutrition-in-women)
- [WHO: Body mass index among adults (Global Health Observatory)](https://www.who.int/data/gho/data/themes/topics/topic-details/GHO/body-mass-index)
- [WHO: Obesity and overweight, fact sheet](https://www.who.int/news-room/fact-sheets/detail/obesity-and-overweight)
- [WHO expert consultation: Appropriate body-mass index for Asian populations, The Lancet (2004)](https://pubmed.ncbi.nlm.nih.gov/14726171/)
- [NHS: Obesity, diagnosis](https://www.nhs.uk/conditions/obesity/)