BMI calculator for adults
Calculate adult BMI, its category and the corresponding weight range at your height, with measurements processed in your browser.
Ile to X% z Y?
X to jaki % z Y?
Zmiana procentowa
Napiwek / VAT / rabata
Średnia / liczba / dane
Netto / brutto / VAT
Enter measurements and read the result
- In the BMI calculator, choose metric, US or UK units before entering your measurements.
- Provide a positive weight and height: kilograms and centimetres, pounds and feet plus inches, or stones plus pounds.
- Read the BMI shown to one decimal place and the category assigned from the unrounded calculation.
- Use the scale and category table to see the thresholds around your result.
- Open BMI Prime for the ratio to 25, and read the limitations before interpreting the weight range.
What this adult calculation helps explain
- Check the relationship between a recorded weight and height.
- Use familiar measurement units without converting them by hand.
- Distinguish the three obesity classes shown in the table.
- See how the weight range associated with BMI 18.5–24.9 depends on height.
- Prepare a numerical reference for a discussion with a health professional.
Understanding BMI and its limits
What formula does the calculator use?
BMI is weight in kilograms divided by height in metres squared. At 70 kg and 1.75 m, 70 ÷ 1.75² gives about 22.9.
How do pounds, feet and stones work?
Imperial measurements are converted before calculation. For example, 154 lb at 5 ft 9 in gives approximately 22.7. In UK units, one stone contains 14 pounds.
Where do the adult categories start?
Underweight is below 18.5; normal is 18.5 to below 25; overweight is 25 to below 30. Obesity classes I, II and III start at 30, 35 and 40 respectively.
Is the displayed weight range a personal goal?
It translates BMI 18.5–24.9 into weight at your entered height. At 175 cm, that is about 56.7–76.3 kg. This mathematical interval is not an individual recommendation.
What does BMI Prime mean?
BMI Prime divides BMI by 25 and is shown to two decimal places. A BMI of 30 gives 1.20; a value of 1.00 corresponds to BMI 25.
Who are these categories intended for?
They are for adults aged 18+, not children or pregnancy. BMI does not separate muscle from fat, and older age and ethnic differences affect interpretation. It is a screening measure, not a diagnosis.