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What’s the maximum PDF file size for public websites?

23 March 2011
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snake eating an elephant

How big is too big? (Note: it isn't a hat). **

Strangely difficult to find good guidelines on a maximum file size for PDF documents.

Craig Thomler from influential Australian blog eGov AU recommended a PDF file size of no more than 2 megabytes:  ‘and you need to have the document in another format to meet accessibility requirements’ (his tweet on 22 March 2011. This ‘other format’ requirement was the subject of hot debate on the AGIMO blog post on Good document design).

At least Craig’s recommendation gives us a bit more leeway than the CUE standard on a Queensland Government web guide

PDF documents larger than the recommended size limit of 200kB should be divided into smaller files and linked to from a HTML cover page. […] For some document types this limit may not be suitable and agencies may develop internal policies to ensure that a size limit of between 200kB to a maximum of 500kB is imposed where appropriate.

Those guidelines were published in early 2008, so Queensland government publishers may well exceed this limit now, but there is still good guidance in their instructions on ‘what makes some PDF files so large?‘.

One of the few notes on file size I found in my research was from the Government of Western Australia, Public Sector Commission, who recommend 4 MB

Why is there a maximum file size of 4mb?

The preferred method for distribution of the annual report is via the web. For people with slow connections, accessing large file sizes can be time consuming and frustrating.
(From: Annual reporting framework, 2011)

I could not find any reference to maximum downloads from other States’ sites.

In the very olden days of the web, we used to think about how long it would take a user to download the file, and Dreamweaver would display this metric for different connection types, and we would argue on what was a reasonable access time. Some NSW council sites still indicate expected download time for PDFs via slower connections.

This was how we currently plan to derive our limits for our site:

  • PDF documents up to 4 MB are publishable within the ordinary workflow. (Because: on a worst possible download speed of 9.6 kB/sec, it would take 59 minutes to download a 4.1 MB file)
  • PDF documents between 4 MB and 12 MB are publishable after approval from our website management unit. (Because: on a worst possible download speed of 9.6 kB/sec, it would take 2 hours 59 minutes to download a 12.3 MB file)
  • Exceptions for files larger than 12 MB will only be made where a specialised audience (not the general public) is the intended primary user of the publication, and this audience is likely to have adequate bandwidth. We should still probably indicate alternative access methods (‘visit your regional office’) for members of the public who wish to view these publications.

(Let’s not argue this too strongly, or the powers that be might turn their attention to the size of our audio and video offerings.)

This standard ought to be relatively easy to enforce – now we move on to educating our publishers on creating more accessible PDF files!

PostPost:  AGIMO does not have a file size limit, but comment: ‘agencies tend to set guidelines for any files above or between 2-5MB. These files are usually split or optimised for the web. We do occasionally see larger files, and sometimes where the content is highly graphical, when it is multimedia or there are special considerations, it may be necessary to provide the larger files” – but they feel that text-based information (e.g. publications) should not exceed 2-5MB.  
 

—-

Le Petit Prince Nursery School, Saint-Nom la Breteche, France. AR+TE Architects inspired by drawings and writings by Antoine de Saint-Exupery.

** I am enchanted with this recently constructed building (right) created in the form of a boa constrictor devouring an elephant.

Thank you Patrick (PATrichotomy) and Saint-Exupery.

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One Comment leave one →
  1. Ryan Tracey permalink
    25 March 2011 11:24 am

    Good article, Penny.

    My personal view is that anything less than 10MB is “OK” for standard web, though anything over 4MB won’t win you any friends.

    Mobile, however, is a diferent story. You really need to keep it under 1 MB, preferably under 500 KB. Otherwise it takes forever to load (at least on my iPhone).

    Frankly I try to avoid PDF downloads wherever possible and go with onscreen text & graphics.

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