The Family Handyman
Precise inside measurements are a cinch, thanks to reader Brian Doss. All you need are two rulers with inch scales that begin exactly from the left end. Butt the end of one ruler into a corner of the space to be measured, and a second ruler—upside down so the scales are facing—into the opposite corner. Read the dimension on the second ruler where it lines up with a whole number on the first, then add the two numbers for the exact inside dimension.