Pick a page in the document that is filled with lines of text. This excludes the first and last page of a document or chapter in a manuscript. Count the number of lines on the page.
Pick 10 lines on a page that appear to contain the most number of words. You may also pick the lines from random pages in the document.
Count the total number of words in the 10 lines. Divide the result by 10 to find the average number of words per line.
Multiply the average number of words per line by the number of lines on a full page. This is the number of words per page. If you want to know the total word count for your document, then multiply this number by the number of pages it contains.