There are 66 books in the standard Protestant Bible: 39 in the Old Testament and 27 in the New Testament.

However, the answer also depends on the tradition you mean:

  • Jewish (Hebrew Bible/Tanakh): 24 books, which correspond in content to the Protestant Old Testament but are grouped and counted differently.
  • Roman Catholic Bible: 73 books (the usual 66 plus 7 Deuterocanonical books, like Tobit and Maccabees, counted as Scripture).
  • Eastern Orthodox Bibles: Often between about 75 and 79 books, as they include additional Old Testament writings beyond the Catholic list.
  • Ethiopian Orthodox Bible: One of the largest canons, with about 81–84 books depending on how certain writings are counted.

If you just say “how many books in the Bible” in most English-speaking church contexts, people usually mean 66.