There is no easy answer to your question, you need to get to work on a calculator.
Depending on the size of book you choose and the paper type Blurb books can go up to 440 pages. A 440 page 13" x 11" book full of text at 9pt would have an awful lot more text than a 40 5" x 8"page trade book with 14pt text.
Give us some examples of book dimensions, word count, word page count, font size, etc. and we may be able to help.