Measure the rug dimensions using a tape measure. Subtract 1 or 2 inches from the width and length and transfer this when measuring the rug pad.
Unfurl the roll of padding and measure the dimensions, subtracting the 1 or 2 inches from both the length and width in step 1.
Create a larger piece of padding to accommodate a rug's length or width by connecting two pieces of padding. Place the padding ends together and secure them by attaching rug tape along the seam to form one solid piece of padding.
Lay the padding on a surface that will not be damaged by a knife blade, such as a concrete garage floor. Cut any excess padding off using a utility knife.
Place the padding on the wood floor where the rug will be laid. Set the rug over the padding and adjust it so it lies evenly over the pad.