I looked at a PDF of the Epic of Gilgamesh, and it was very pretty. Then, I decided that I wanted to purchase the physical copy of the book. While the version that I read online, which I thought was very thorough, was only of maybe 30 pages, the books to buy from Amazon were sometimes 130 pages, some well into the 200s, and none less than 50. I imagine that the version I read could not have been one in entirety, and I found it odd that these books had so many different lengths.
Assuming the online version you read was by AINA (the Assyrian International News Agency), which indeed sits at 27 pages (and is the third result when I Googled "Epic of Gilgamesh"), note that the PDF pages are US Letter-sized. Most print books would have pages with half those dimensions (well, not quite half, but ...) or a fourth of the area, and so around 4 times the page count (100+). This edition is by N. K. Sandars, who is also the editor of the 1972 Penguin Classics edition, which has 127 pages. (The one Gallifreyan talks about would be the 2003 edition, which has 228 pages.)