Google Webmaster Tools is full of useful things, including mobile web page errors and warnings. A new warning that was spotted was on the size of your mobile web pages. We have two threads on the topic, one at WebmasterWorld and the other at Google Groups. The threads report the same "Mobile crawl errors":
Document size too large
Google currently has zero documentation on exactly how large is too large for mobile web pages. But WebmasterWorld moderator, jdMorgan figures the threshold stars somewhere at 21kB to 30.3kB being too large.
Phil Payne at the Google Groups thread links to the W3C page size limit section, which says:
PAGE_SIZE_USABLE Machine Test: Measure the total size of the markup for a page; check that it does not exceed 10 kilobytes for the Default Delivery Context.
Human Test: Check that the page is still usable (e.g. not cut in the middle of a sentence, just before the end of a section, and so on).
PAGE_SIZE_LIMIT Machine Test: Measure the total size of markup and images for a page; check that it does not go over the allowed size for the device - 20 kilobytes for the Default Delivery Context.
In short, the maximum page size for mobile pages should not be larger than twenty kilobytes. As Phil explains, this was written in 1996 and should likely be changes with the 3G standard being adopted by many mobile phones, plus the iPhone and soon Google Android phone to allow faster and more fluid mobile browsing.
So where does Google hold? Somewhere between 21 kilobytes and 30.3 kilobytes?