Adult BMI Calculator
Calculate adult BMI from height and weight and see CDC adult reference categories for people aged 20 and older.
Your inputs
Adult BMI Results
22.857143 kg/m²
Healthy weight
Full result table
| CDC adult category | BMI range (kg/m²) |
|---|---|
| Underweight | Below 18.5 |
| Healthy weight | 18.5 to below 25 |
| Overweight | 25 to below 30 |
| Obesity class 1 | 30 to below 35 |
| Obesity class 2 | 35 to below 40 |
| Obesity class 3 | 40 or more |
BMI is a screening measure, not a diagnosis or body-fat measurement. Adult categories are not suitable for children; pregnancy and individual circumstances require other assessment.
Let’s work it out.
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How to use Adult BMI Calculator
- Enter weight (kg), height (cm), age (years).
- Calculate and compare the labelled result views. Check that every input uses the displayed unit.
- Read the worked example and limits before applying the answer.
Worked example
70 kg at 175 cm gives BMI 22.86 kg/m².
Formula, accuracy & limitations
BMI = weight in kilograms ÷ height in metres squared.
BMI is a screening measure, not a diagnosis or body-fat measurement. Adult categories are not suitable for children; pregnancy and individual circumstances require other assessment.
Calculations use your inputs. Main numeric values show up to six decimal places, percentages up to two, and chart labels up to four. Time results use hours, minutes and seconds. Very small nonzero values use scientific notation.
Read the measurement reference ↗Use the adult reference for age 20 and older
Enter kilograms, centimetres and age. The page restricts this calculator to adults aged 20 or older and uses weight divided by height in metres squared. Adult category boundaries are evaluated using the unrounded result, so a rounded display cannot move the calculation into another category.
A screening category is not a diagnosis
The reference bands follow CDC adult categories. The diagram displays an axis from 0 to 50 with a clearly clipped marker for higher values; the numeric result remains uncapped. BMI does not directly measure body fat and needs clinical context, including pregnancy, muscularity and other individual circumstances.
Frequently asked questions
Can children use these category bands?
This page rejects ages below 20. Children and teens require age- and sex-specific assessment rather than these adult bands.
Does the category use the rounded displayed BMI?
It uses the unrounded calculation. Display rounding is applied only after the category is selected.
Why can the category differ from the rounded BMI on screen?
Categories use the unrounded number. A value just below 25 may display as 25 after rounding while still falling below the 25 category boundary.
Can this tell whether my weight is mostly muscle or fat?
No. BMI relates mass to height and cannot distinguish muscle, fat or fluid. It is a screening measure, so personal interpretation requires more context.
