Your result
What your result means
At 5 ft 9 in and 170 lb, your BMI is 25.1, which the CDC classifies as “Overweight” for adults 20 and older. For your height, a BMI between 18.5 and 24.9 corresponds to 125 lb – 169 lb; you are about 1 lb above that range. BMI is a screening number only — it does not measure body fat directly.
The math
Formula and sources
BMI = weight (kg) ÷ height (m)² US units: BMI = 703 × weight (lb) ÷ height (in)²
- Underweight
- below 18.5
- Healthy weight
- 18.5 to < 25
- Overweight
- 25 to < 30
- Obesity
- 30 or higher
We convert pounds and inches with the exact factors (1 lb = 0.45359237 kg, 1 in = 2.54 cm), which is what the 703 shortcut approximates. Children and teens use age- and sex-specific percentiles instead.
Sources we checked this against
- 1Adult BMI Categories / BMI Frequently Asked QuestionsCenters for Disease Control and Prevention · cdc.gov
- 2Calculate Your Body Mass IndexNational Heart, Lung, and Blood Institute (NIH) · nhlbi.nih.gov
Formula last checked 2026-11-04. Found an error? Tell us and we will fix it.
Step by step
Two worked examples
CDC’s example adult
Your BMI
30.4
- Units
- US (ft, in, lb)
- Height (feet)
- 5 ft
- Height (inches)
- 8 in
- Weight
- 200 lb
The CDC uses a 5 ft 8 in adult weighing 200 lb: 703 × 200 ÷ 68² = 30.4, in the “Obesity” category.
Same height, 150 lb
Your BMI
22.8
- Units
- US (ft, in, lb)
- Height (feet)
- 5 ft
- Height (inches)
- 8 in
- Weight
- 150 lb
At 150 lb the BMI falls to 22.8 — “Healthy weight”. The healthy range for 5 ft 8 in is 122 lb – 164 lb.
| Result | Example 1 | Example 2 |
|---|---|---|
| Your BMI | 30.4 | 22.8 |
| Category | Obesity | Healthy weight |
| Compared with that range | about 36 lb above | within |
Questions
Frequently asked questions
Is BMI accurate for athletes?
Not very. Muscle is dense, so muscular people can have a high BMI with little body fat. A waist measurement or a body fat estimate gives more context.
Does BMI differ for men and women?
For adults the same categories apply regardless of sex or age. Women tend to carry more body fat than men at the same BMI, which is one reason BMI is only a screening tool.
Can I use this for my child?
No. For ages 2 to 19, BMI must be compared with growth charts for the child’s age and sex. Use the CDC’s Child and Teen BMI Calculator.
What should I do if my BMI is out of range?
Treat it as a prompt for a conversation with a healthcare professional, who can look at blood pressure, lab results, waist size and other factors.