The English edition of Wikipedia Encyclopedia contains around 3 million articles as of now and if someone were to print the entire Wikipedia encyclopedia into a book, the size of that book would roughly be equivalent to 952 volumes of the Encyclopedia Britannica.
Not sure if anyone is willing to go that far but a student in UK has actually converted 0.01% of the Wikipedia encyclopedia into a printed book. See some pictures below:
Also see: How to Print Wikipedia Articles
This Wikipedia book has some 5,000 pages and it’s a compilation of 400+ featured articles all picked from Wikipedia. And, as you can easily make out from the photographs, the book is huge - it’s about 1ft 7in. high or just as tall as a 30" widescreen monitor.
Related: Guide to Useful Wikipedia Tools