BMI Calculator
BMI calculator in pounds, feet and inches: body mass index and the CDC weight category for adults.
Editorial review: Farrow (pseudonym; identity and professional credentials are not disclosed). This page is for educational purposes, not professional advice.
Your inputs
Results update as you type. Nothing you enter leaves your device.
Results
- Category
- Overweight
Example with the starting values
These results use the calculator's initial inputs. Change the values above to calculate your own estimate.
Inputs
- Weight
- 170 lb
- Height (feet)
- 5 ft
- Height (inches)
- 9 in
Results
- BMI
- 25.1
- Category
- Overweight
How does the BMI Calculator work?
Body mass index (BMI) is a screening number that relates weight to height. In US units, BMI = 703 × weight (lb) / height (in)². For example, 170 lb at 5 ft 9 in (69 in) gives 703 × 170 / 4,761 = 25.1.
For adults age 20 and older, CDC categories are under 18.5 underweight, 18.5 to 24.9 healthy weight, 25 to 29.9 overweight, and 30 or more obesity. Children and teens use age- and sex-specific percentiles instead.
At 5 ft 9 in, the adult healthy-weight BMI range of 18.5 to 24.9 corresponds to roughly 125 to 168 lb. The calculator reports the BMI number and category, but the categories are screening ranges rather than a diagnosis or a personal health target.
BMI does not measure body fat directly or distinguish fat from muscle and bone. A muscular person may have a high BMI without high body fat, while an adult with a BMI in the healthy range can still have health risks. A clinician may consider waist measurement, medical history and other factors.
This calculator applies adult categories only. It is not intended for children or teens, where age- and sex-specific growth charts are used, and it does not adjust for pregnancy. Discuss health concerns or weight changes with a qualified healthcare professional.
The BMI category is determined by the unrounded calculation, while the displayed BMI is rounded to one decimal place. A displayed value near 25 or 30 can therefore appear to sit on a threshold even when the underlying number falls just to one side. Treat the category as a broad screening signal, not a sharp boundary between health states.
Adult BMI uses the same formula and category ranges regardless of sex or age. That consistency makes BMI useful for population screening, but it does not account for differences in body composition or changes that can accompany aging. A clinician can interpret the number alongside blood pressure, lab results, family history and other measures.
Sources
Frequently asked questions
What is a healthy BMI?
For adults, a BMI of 18.5 to 24.9 is considered healthy by the CDC. At 5 ft 9 in, that range is about 125 to 168 lb.
How do I calculate BMI?
Multiply weight in pounds by 703, then divide by height in inches squared. For 150 lb at 5 ft 5 in (65 in), BMI = 703 × 150 / 4,225 = 25.0.
Is BMI different for men and women?
No. Adult BMI uses the same formula and categories for men and women. Women tend to carry more body fat at the same BMI, which is one limit of the measure.
Is BMI accurate?
BMI is a screening tool. It does not tell muscle from fat, so athletes can score as overweight. Talk to a doctor for a full assessment.