You can check the size of your PDF in just a few steps:
On a Mac:
Open the PDF in Preview.
Click Tools in the top menu.
Select Show Inspector.
Click the ruler icon to view the document dimensions.
On a Windows PC (Adobe Acrobat):
Open the PDF in Adobe Acrobat.
Click File.
Select Properties.
Under the Description tab, look for the Page Size section.
The page size listed will show the finished dimensions of your file. Be sure to compare this to the product size you selected (including bleed, if required) to ensure your file is set up correctly.