Nomograms are usually created using the set of units most appropriate and convenient for the expression or relationship of interest. The best way to create a nomogram in the units of choice is to start with an algebraic relationship expressed in terms of these units. As an example, consider the area of a circle

*A* = 3.14159 *
*R*^{2}

where *R* is in units of meters and *A* is in units of meters
squared. But say we wish to use centimeters for radius *R* and square
feet for area *A*. To do so, we convert the expression as follows:

where we have employed the conversions: 1.0 sq ft = .0929 m^{2}
& 1.0 cm = 0.01 meters. By combining the constant factors, the
above equation reduces to the form:

Now, entering a radius value in centimeters into the equation gives the value for area directly in square feet. This unit conversion method may be employed to convert any expression into a more convenient form for a nomogram with any set of units. It is only necessary to input the correct coefficient in the dialogue box when the nomogram is initially created. Note that it is also very important to provide the correct units for all variables in the dialogue box.