The FPS system of units has the foot, pound, and second as its base units.  Unlike modern systems of units, composite dimensions are not necessarily represented by a product of powers of the base units. For example, the unit of power, the horsepower, is not equal to one square foot pound per cubic second.

When used in conjunction with the UseSystem command, the FPS system sets the following units for the given dimensions.

To enter a unit in 2-D Math input, select the unit from the appropriate Units palette. If the unit you want is not there, select $\mathrm{unit}$ and then enter the unit.

When you edit a unit, double brackets appear around it.

$\mathrm{Units}\left[\mathrm{UseSystem}\right]\left('\mathrm{FPS}'\right)$

$\mathrm{with}\left(\mathrm{Units}\left[\mathrm{Standard}\right]\right)\:$

$5\mathrm{Unit}\left(\frac{{'\mathrm{ft}'}^2'\mathrm{pound}'}{{'s'}^2}\right)$

$5⟦\frac{\mathrm{lb}{\mathrm{ft}}^2}{s^2}⟧$

$\mathrm{combine}\left(\,'\mathrm{units}'\right)$

$\frac{30480}{196133}⟦\mathrm{lbf}\mathrm{ft}⟧$

$\frac{\mathrm{Unit}\left('s'\right)}{}$

$\frac{3048}{10787315}⟦\mathrm{hp}⟧$

$\frac{{\mathrm{Unit}\left('\mathrm{yard}'\right)}^2}{}$

$\frac{5}{9}⟦\frac{\mathrm{lb}}{s^3}⟧$