Yes, you can print checks on different sizes, but in order to do that, you will have to change the Printing Preferences. Simply start the Peachtree application and go to File > Print. You should have a check loaded while doing this. While you are in the Print menu, go to Preferences > Layout and change the paper on the right drop down menu. Accept the changes and continue with the printing through the Print button. If the application uses custom templates to print the checks, you should adjust the size of those templates as well. This can be done within the application's interface.