you can change length units to FEET,INCH,FRACTION and that will display length measurements in fractions.
(BEWARE: if you do this, all inputs will be in FEET,INCH,FRACTION also! If you make a line .5 long, it will be 6 inches (1/2 foot). You have to add " behind .5 to make it 1/2 inch. Or change units back to INCHES)