The size Transfer you decide on ultimately is up to you! It is all a matter of personal preference. I have seen many different variations, but I will list the sizes below and then this way you can ultimately decide what works best for you and your business!
Please remember, all sizes listed are in INCHES and it is the WIDTH of the design. The length varies design to design. I let them auto adjust their size. I don't want them to look stretched, so letting the design auto adjust prevents that from happening.
3 Inches Wide:This size is used for mugs, shirt pockets, can coolers.
I have also had some use this size for newborn baby rompers.
5 Inches Wide:
This size is used for baby rompers, toddlers and children.
(Remember, this means the image is adjusted to fit the largest it can on a letter size piece of paper [8.5 inches x 11 inches])
This is when the biggest personal preference comes into play. I have MANY customers that use Letter Size for ALL adult shirts. I have some that use Letter Size only for XS - M.
10.5 Inches Wide:
This size is used for Adults L-XL
12.5 Inches Wide:
SOME Designs come in this larger size, some do not. It depends on the design.
This size is used for XL-XXL