I was taught in high school, when writing essays, that you can estimate how many words you've written by counting the words on a single line and then multiplying it by how many lines you've written. It works out to be a very broad estimation, especially if you've written short lines of dialogue.
today I wrote 3031 words: one chapter for one of my storys with 902 words and alot rough ideas and dialoges for other projects with 2129 words but i didn't wrote a single word over the last three or four days, but there where neighter motivation nor inspiration back then. The chapter I wrote brings the first fantasy elements in my scifi world and it was very difficult for me to make it "fit"
As of right now, I've written 2,009 words in one fan fiction i'm writing and 16,047 in another (not sure if these count) so if i add that I've written 18,056 words total. Others are finished so i didn't count those, unless you want me to.