BMI calculator
Enter height and weight to calculate adult BMI, weight category, new BMI as a comparison value and an estimated normal weight range.
Calculate BMI
What BMI is
BMI, or body mass index, describes weight in relation to height. The traditional measure is calculated by dividing weight in kilograms by height in meters squared. On this page, the weight category is based on adult BMI classification.
BMI formula
- BMI = weight kg / height m².
- Example: 80 kg / 1.80² = 24.69.
- New BMI = 1.3 × weight kg / height m^2.5.
- The normal weight range is calculated from the traditional BMI range 18.5-24.9.
New BMI is an alternative formula that adjusts the effect of height differently. In Calculic it is shown as a comparison value and is not used to choose the weight category.
Example calculation
A person who is 180 cm tall, or 1.80 m, and weighs 80 kg has a traditional BMI of 80 / 1.80² = 24.69. That is within the normal weight range for adults under the traditional classification.
BMI categories for adults
- BMI below 18.5: underweight.
- BMI 18.5-24.9: normal weight.
- BMI 25.0-29.9: overweight.
- BMI 30.0-34.9: obesity class 1.
- BMI 35.0-39.9: obesity class 2.
- BMI 40.0 or higher: obesity class 3.
The categories are intended for adults. WHO uses BMI 25 or higher as a threshold for overweight in adults and BMI 30 or higher as a threshold for obesity.
Normal weight range for your height
The calculator shows the approximate weight interval that corresponds to BMI 18.5-24.9 for the height you enter. If the height is 180 cm, the range is about 59.9-80.7 kg.
Limitations
BMI only uses height and weight. It does not distinguish between muscle mass, fat mass, fluid and bone, and it does not show how body fat is distributed.
A very muscular person can have a high BMI without the result telling the full picture. Children and teenagers need age- and growth-specific assessment rather than fixed adult cutoffs.
Health disclaimer
BMI is a broad screening measure. The calculator does not provide a diagnosis and is not medical advice. If you are concerned about weight, eating or health, use a qualified health professional for an individual assessment.
Frequently asked questions
How is BMI calculated?
BMI is calculated by dividing weight in kilograms by height in meters squared.
What is a normal BMI?
For adults, the traditional normal weight BMI range is usually 18.5-24.9.
What BMI counts as overweight?
For adults, BMI 25.0-29.9 is in the overweight range.
What BMI counts as obesity?
For adults, BMI 30.0 or higher is in the obesity categories.
What is new BMI?
New BMI is an alternative formula that weights height differently from traditional BMI. This calculator shows it only as a comparison value.
Why can BMI be misleading?
BMI uses only height and weight. It does not know how much of the weight is muscle, fat, fluid or bone, and it does not measure body composition directly.
Can this BMI calculator be used for children?
No. This calculator uses adult BMI cutoffs. Children and teenagers need age- and growth-specific assessment.