The standard size for a printed cookbook is 5 1/2 x 8 1/2.
However we do also offer the ability to create a cookbook that is 8 1/2x11 in size. This will allow more recipes to be on a single page, but overall the cost is slightly higher than the standard size.
You can selected your cookbook size in the Design Center using the Cookbook size link which is the last option in the First Steps section.