These dresses are very quick to make. I take the t-shirt and measure down from the point that would be at the same height as the top of a pillowcase dress (DO NOT measure from the neck... your dress will be too short). I decide where to cut off my t-shirt. For example: from that upper chest area to the bottom of t-shirt in number one (the horse dress) was 11 inches... I was making a size 4 so my fabric needed to be 13 inches long plus the hem. The t-shirt part of the dress can be different lengths... depending if you want an empire style dress or a low-waisted dress or also depending on where the design is on the t-shirt if there is one. I attach the two parts together using the ruffler foot on my serger. If you do not have a serger, you will need to gather the fabric and sew to the t-shirt using a zigzag stitch (if you use a straight stitch the fabric will ravel and you will not have the give you need when a child pulls the dress over their head).