The measurements are based off a dollar. I wanted it to be big enough to hold folded bills. With that in mind I took five 3"x5" cards and cut them down to 2&3/4" wide. I did the same to another 5 cards and taped them offset so they measured 6&1/4" long (a dollar is 6" long). These taped off cards served as my form. Having completed the project I would recommend adding 3/4" more length to the form past the length of the bill. I only did 1/4" longer and it left the bills hanging out some.