My garden is 25LX10W this gives me a total 70ft perimeter I planned to have the border be about one foot wide. The six bags of mulch was plenty for this job with a little excess. I decided to just cover the existing grass this the ground cloth. But make sure that your grass is trimmed up short, this will make things easier later on.
First I laid out the cloth along the length of the garden with a foot of excess on each end. I then cut the 25ft side first then I continued to cut the shorter 10ft. side. The cloth is 30 inches wide so made a cut strait down the middle of the cloth so that I had four 15 inch wide strips for the sides.