Roll out the area rug and lay it flat on the surface it will be used on.
Measure the size of the rug with a tape measure. Do not include fringe or tassels when measuring.
Subtract two inches from the overall length and two inches from the overall width—this is the size the rug pad needs to be. For example, a rug measuring 48 inches by 72 inches would require a rug pad sized at 46 inches by 70 inches.
Cut the rug pad to the calculated size using a utility knife or a pair of sharp scissors. The size does not need to be perfect. As long as the pad is hidden under the rug, an angled or crooked cut will never be seen.
Place the cut pad onto the floor where it will be used and center the area rug over it.