Body mass index (BMI) is a measure of body fat based upon your height and weight that applies to **adult** men and women only. The formula in imperial freedom units is as follows.
$$
\text{BMI}=703.0717*\frac{\text{Pounds}}{\text{Inches}^2}
$$
For a 175 pound human that is 73 inches tall this works out to a BMI of...
$$
\begin{align}
\text{BMI}&=703.0717*\frac{\text{Pounds}}{\text{Inches}^2}\\
\\
\text{BMI}&=703.0717*\frac{175}{73^2}\\
\\
\text{BMI}&=703.0717*\frac{175}{5329}\\
\\
\text{BMI}&=703.0717*0.032839181835241\\
\\
\text{BMI}&=23.088299399512105
\end{align}
$$
...approximately 23.1. BMI breakpoints for weight healthiness are generally considered as follows...

BMI Range|Classification
--|--
Below 18.5|Underweight
18.5-25|Normal
25-30|Overweight
30-35|Class 1 Obesity
35-40|Class 2 Obesity
Above 40|Class 3 Obesity

Given the chart above we can see that our 175 pound 73 inch tall human is considered normal weight.