What is a MediaBox?A PDF describes the content and appearance of one or more pages, and also contains a definition of the physical size of those pages. There can be up to five different definitions in a PDF relating to the size of its pages: MediaBox, CropBox, BleedBox, TrimBox and ArtBox. These are called the page boxes or boundary boxes. PDF boxes describe the page geometry of PDF. They are used frequently in the printing industry.
For the average user, the MediaBox equals the actual page size. It specifies the width and height of the page and is meant to represent what the user would see if they printed out the PDF page. It does not have quite the importance for an interactive document displayed on the screen, but it is very important to page geometry.
The PDF MediaBox describes the extent of the medium on which the page is to be printed. This includes any surplus area outside the finished page used for printing marks, bleed etc. MediaBox contains all the other boxes in the PDF, making it the largest box. It is the only one that is absolutely necessary. If the other boxes are not further defined, they correspond in size to the Mediabox.
Find out more about the other PDF boxes in the following article.