In the Natural Units environment, the equality and inequality operators (=, <, <=, >, >=, and <>) are modified so that they perform the necessary operations on expressions with units.

The properties of the five arithmetic operations are:

where a and b are units; A and B are coefficients; and r is the conversion factor from the unit  to the unit a.

with(Units[Natural]):

3*ft=yd;

evalb((1));

1.60*m < mi;

evalb((3));

30.48*cm = ft;

evalb((5));

3 * ft + 3*`in` = m;

evalb((7));