Cut off the bottom hem of the T-shirt. Measure the circumference of baby’s head and divide by 2 (or get your hands on another hat that you know fits and measure it) to get x". Mark that measurement from one of the corners at a 45-degree angle from the bottom edge of the T-shirt.
Mark 13" from the bottom up the side edge. Connect that mark with the end of the line you made in step 1.
Cut along the lines.
Pin along the open diagonal edge, right sides out. Sew a running stitch or whipstitch along the pinned edge for an external seam.
Remove the pins and tie the tip of the hat in an overhand knot, leaving about 2" at the top. The bottom edge will curl naturally.
This project is excerpted with permission from <a href="http://www.amazon.com/gp/product/0761154108/ref=as_li_qf_sp_asin_il_tl?ie=UTF8&camp=1789&creative=9325&creativeASIN=0761154108&linkCode=as2&tag=craftfocom-20">"Generation T: Beyond Fashion"</a> by Megan Nicolay and published by Workman Publishing.