Is there a way to get the PDF page size (width and height) in millimeters?

[araichev]

Couldn't find this feature in the docs and wondering if it's possible, because sometimes i want to check if a PDF is size A4 or A3.

[pubpub-zz]

@araichev
the mediabox page property returns the page size in user space units (1 user space unit = 1/72" = 0.35277777777777775 mm)

[MartinThoma]

First you have to know that PDF pages have several boxes:

• mediabox
• cropbox
• artbox
• trimbox
• bleedbox

You can get those like this:

>>> from PyPDF2 import PdfReader
>>> reader = PdfReader("issue-856.pdf")
>>> reader.pages[0].mediabox
RectangleObject([0, 0, 595.276, 841.89])

The specs say:

(Required; inheritable) A rectangle (see Section 3.8.4, “Rectangles”), expressed in default user space units, defining the boundaries of the physical medium on which the page is intended to be displayed or printed (see Section 10.10.1, “Page Boundaries”).

Chapter 4:

To avoid the device-dependent effects of specifying objects in device space, PDF defines a device-independent coordinate system that always bears the same relationship to the current page, regardless of the output device on which printing or displaying occurs. This device-independent coordinate system is called user space.
[...]
The length of a unit along both the x and y axes is set by the UserUnit entry (PDF 1.6) in the page dictionary (see Table 3.27). If that entry is not present or supported, the default value of 1 ⁄ 72 inch is used. This coordinate system is called default user space.

You will be able to access a pages user_unit after the next release (see #1336 ) more conveniently.

So the example page above has a media-box of a height of 841.89 * (1/72) inch and a width of 595.276 * (1/72) inch.

You could compare against PyPDF2.PaperSize.A4 which is defined as (595, 842) - always in the default user space units of 1/72 inch.