About this imperial BMI calculator
This version of our BMI calculator starts in imperial units — pounds for weight, feet and inches for height — the units used in the United States. The imperial BMI formula multiplies weight ÷ height² by a conversion factor of 703, so the result is identical to the metric calculation: for example, 160 lb at 5′10″ (70 inches) gives BMI = 703 × 160 ÷ 70² ≈ 23.0, which falls in the healthy range. The same categories apply as everywhere else: under 18.5 is underweight, 18.5–24.9 healthy, 25–29.9 overweight, 30+ obese. Prefer kilograms and centimetres? Use the metric BMI calculator.
Frequently asked questions
- How do I calculate BMI with pounds and inches?
- Multiply your weight in pounds by 703, then divide by your height in inches squared: BMI = 703 × lb ÷ in². This tool does it for you — just enter pounds, feet and inches.
- What is a healthy BMI in imperial units?
- BMI categories are unit-independent: 18.5–24.9 counts as the healthy range whether you calculate in pounds and inches or kilograms and metres. For a 5′10″ adult that works out to roughly 129–173 lb.
- Why does the imperial BMI formula use 703?
- 703 is the conversion factor that makes pounds-and-inches give the same number as the metric kg/m² formula, so BMI values are comparable worldwide.