Publisher – PDF export is always 0.1mm x 0.1mm too large

[dcmartns]

Hello, I’m trying to create a business card with the dimensions 85x58mm.

However, the exported PDF is always 85.1x58.1mm. I really don’t understand it.

Is this a feature or a bug? I can’t upload the document to the printer because it’s too large.

 

Version: 2.5.7 macOS 15.2

[NotMyFault]

Affinity rounds up to whole pixel. 

You can see the issue when you activate pixel view mode, and simply create a red rectangle covering the whole canvas. You will see a lighter red seam at the right and bottom, caused by a fractional pixel. At exports, this gets rounded up and causes the extra size.

To avoid, you may play with the DPI setting which avoids fractional pixel based on the given size in mm.

[thomaso]

2 hours ago, dcmartns said:

the exported PDF is always 85.1x58.1mm

Are you sure these are objectively accurate values? Where do you read this PDF page size? Attached a 85x58 mm PDF, open this file in APub and check its sizes. It appears Apple's Preview.app reports another size than APub and Acrobat, maybe that's how it rounds decimal numbers.

Since PDF has the unit 'points' * there is no absolutely perfect size in mm because of PDF doesn't create fractions of points, so it results in fractions of mm, for instance for the mediabox of the attached PDF (but still less than additional 0.1 mm).

85x58.pdf   

[dcmartns]

It is true that Adobe Acrobat Reader sometimes displays the correct size. However, when I try to upload the PDF for a print job, it gets rejected because the size is incorrect.

I have previously created many print products with Adobe InDesign and have never encountered such behavior.


... And how, please, can a print product not be measured in millimeters?

Edited December 22, 2024 by dcmartns

[Oufti]

Adobe uses points (= 1/72") as internal unit for its calculations and for PDF. 
Affinity seems to use pixels internally. 
None of these converts exactly in mm, thus small rounding errors occur. 

Cells in grey are rounded:

 

You can go to Document setup, change the unit to pixels and try to round down the size of your document to an exact number of pixels (for conveniency don't rescale anything else). 

The difference will be almost unnoticeable but automated processes shouldn't reject your file anymore.