Memory quilt with 12x12 inch squares. Layer of batting, backing and binding edge. Shirts will depend on if you are wanting just the front of shirt or if backs can be used.  
baby - 3x3 - 9 shirts
Lap - 4x4 - 16 shirts 
twin - 4x6 - 24 shirts
full - 5x6 - 30 shirts
large throw - 6x6 - 36 shirts
Queen - 6x7 - 42 shirts