Use a recent measured weight and switch units beside the field when needed.
HEALTH / SCREENING RATIO
Adult BMI Calculator
Calculate adult body mass index using your preferred weight and height units, then see the WHO reference classification with its limitations visible.
- 01 Calculated in this tab
- 02 Values stay in this browser tab
- 03 Use boundary
WEIGHT-TO-HEIGHT RATIO / ADULT SCREENING VIEW
See how one adult height turns into both a BMI result and a weight window
BMI becomes more useful when the ratio and its same-height weight window stay visible together. With the reviewed defaults 70 kg and 170 cm, the calculator converts height to 1.70 m, squares it to 2.89, returns BMI 24,22, and places that result in the WHO adult Healthy weight band. At the same height, the healthy reference window on this page runs from 53,5 kg to 72 kg.
Worked default example
- Entered adult measurements
- Weight = 70 kg. Standing height = 170 cm.
- Convert height to metres
- 170 cm / 100 = 1.70 m.
- Square the height
- 1.70 x 1.70 = 2.89.
- Divide weight by height squared
- 70 kg / 2.89 = 24,22.
- Invert the same height for the healthy window
- 18.5 x 2.89 = 53,5 kg, 24.9 x 2.89 = 72 kg.
- Returned page result
- The calculator reports BMI 24,22, WHO adult classification Healthy weight, and the same-height healthy reference window 53,5 kg to 72 kg.
What to enter and how to read the result
Enter a recent adult body weight and choose kilograms, pounds, or stone beside the field. Enter standing height without shoes and choose centimetres, metres, total inches, or decimal feet. The result panel then shows the BMI ratio first, followed by the WHO adult class, the lower and upper reference weights for the same height, and the height used in the calculation.
What the calculator actually does
Nirmion normalises the chosen units to kilograms and metres, applies BMI = weight / height^2, and then compares the ratio with the WHO adult reference bands. The same page also inverts the formula at your height with BMI 18.5 and 24.9 so the healthy reference weight window stays visible beside the main result.
Assumptions behind this page
The model assumes one recent body weight, one standing height, adult use only, and correct unit selection for each field. BMI is a screening ratio built from weight and height; it does not directly measure body-fat percentage, waist distribution, fitness, or disease risk in one individual.
Where this model stops helping
Do not use this adult BMI page as a diagnosis or treatment decision. Children and teenagers need age- and sex-specific growth references. Pregnancy, unusual muscularity, oedema, amputation, some ethnicity-related risk contexts, illness, and wider clinical context can all change how a BMI result should be interpreted.
HEIGHT-LOCKED VIEW
At one fixed height, BMI becomes a weight window. For 170 cm, the healthy reference range on this page is 53,5 kg to 72 kg.
Default BMI mapped onto the WHO adult bands
A horizontal BMI ruler with WHO adult bands from underweight through obesity class III, a marker at BMI 24,22, and a note that the healthy-weight window at 170 cm runs from 53,5 kg to 72 kg.
The calculator converts this to 1.70 m before squaring it.
This reviewed default result lands in the WHO adult Healthy weight band.
These are the page's BMI 18.5 and 24.9 inverse weights for the same 170 cm.
Healthy window at 170 cm: 53,5 kg to 72 kg.
REVIEWED BMI SOURCE
Why the page uses WHO adult bands
The calculator definition cites the World Health Organization fact sheet on overweight and obesity, which includes adult BMI reference cutoffs. Nirmion uses those adult bands for a first screening view and keeps the limitations beside the result instead of presenting BMI as a diagnosis.
Read the WHO fact sheet on adult BMI, overweight, and obesityBMI QUESTIONS
Adult BMI calculator FAQs
Does the BMI change if I switch from kilograms to pounds or from centimetres to inches?
No. The page first normalises the selected units to kilograms and metres, so equivalent inputs produce the same BMI 24,22 and the same WHO adult classification.
Why does this BMI calculator show a reference weight range for my height?
The tool inverts the same BMI formula at your entered height using BMI 18.5 and 24.9. For the reviewed default height 170 cm, that produces 53,5 kg to 72 kg.
Can I use this page for teenagers, pregnancy, or athletic body composition?
No. This page is bounded to adults and BMI is only a screening ratio. Growth charts, pregnancy care, muscular build, oedema, amputation, and clinical context need different assessment models.