What is the BMI formula in imperial units?

BMI = (weight in lbs × 703) ÷ (height in inches)². The factor 703 converts the result to the same scale as the metric formula.

What is a healthy BMI for adults?

The WHO defines a healthy BMI as 18.5 to 24.9 for adults, regardless of sex or age. This range is associated with the lowest risk of weight-related health conditions.

Does BMI apply to children?

BMI is interpreted differently for children and teens. It is compared against age- and sex-specific percentile charts, not fixed thresholds. This calculator is intended for adults (18+).

Is my data sent to a server?

All calculations are pure JavaScript running in your browser. Our servers are not involved at any point.

BMI calculator, imperial (lbs / ft in)

Enter your weight in pounds and height in feet and inches to calculate your BMI and see your WHO weight category. Runs entirely in your browser.

Height

Weight (lbs)

How it works

Pounds are converted to kilograms (multiply by 0.453592) and your feet plus inches are converted to metres (1 ft = 0.3048 m, 1 in = 0.0254 m). Those metric values then go through the WHO formula weight(kg) / height(m)^2 to produce a BMI on the same scale used worldwide, which is matched against the WHO weight categories for the label that appears below your result.

Processing runs in your browser

All calculations happen locally in your browser tab. Our servers are not involved at any point.

Technical specification

The BMI formula was standardised by the WHO Technical Report Series 894 (2000): BMI = weight(kg) / height(m)². WHO classifies BMI into four categories for adults: Underweight (<18.5), Normal weight (18.5–24.9), Overweight (25.0–29.9), and Obese (≥30.0). BMI does not distinguish between muscle and fat mass and is intended as a population-level screening tool, not an individual diagnostic.

Formula: weight(kg) / height(m)²
Standard: WHO Technical Report Series 894 (2000)
Normal range: 18.5 – 24.9
Browser API: Pure JavaScript arithmetic. No library

Related operations

To estimate daily energy needs, try the calorie calculator. For body composition with circumference measurements, use the body fat calculator. To find a reference weight range for your height, see the ideal weight calculator.

Frequently asked questions

What is the BMI formula in imperial units?: BMI = (weight in lbs × 703) ÷ (height in inches)². The factor 703 converts the result to the same scale as the metric formula.
What is a healthy BMI for adults?: The WHO defines a healthy BMI as 18.5 to 24.9 for adults, regardless of sex or age. This range is associated with the lowest risk of weight-related health conditions.
Does BMI apply to children?: BMI is interpreted differently for children and teens. It is compared against age- and sex-specific percentile charts, not fixed thresholds. This calculator is intended for adults (18+).
Is my data sent to a server?: All calculations are pure JavaScript running in your browser. Our servers are not involved at any point.

Last reviewed May 26, 2026