Marcus Beck, a PhD candidate at the University of Minnesota, has created a chart demonstrating the varying average lengths of PhD dissertations by discipline.
According to io9, “Beck took the pressure of readying for his defense and channeled it toward an incredibly interesting (if entirely thesis-unrelated) side project. For Beck, that meant coding a data scraper that could gather information about students’ dissertations (page-length, year and month of graduation, research focus, etc.) from the University of Minnesota’s electronic thesis database.”
Beck’s calculations are based on data from University of Minnesota PhD dissertations from 50 departments, so they may or may not be representative.
But, historians will not be surprised to find that the longest dissertations in Beck’s data are those of history PhDs, with an average of almost 300 pages.
History PhD dissertations are arguably longer than those in other fields because of the discipline’s archival sources, citation formats, historiographical frameworks, and demanding standards of evidence.
For the record, my own PhD dissertation came in at 731 pages. Given its weight, perhaps we should consider assessing dissertations in pounds?