How Long Does it Take to Write a Book?

I have been asked this many times, so I decided to figure it out.

These are minimum times for me. Other authors may be slower or faster; it varies with the individual.
The rough draft takes me between 30 and 45 10-hour days, depending on the length of the book, which is approximately 300 to 460 hours.
The second draft takes me about thirty 8-hour days, times two authors, for approximately 480 hours.
The manuscript is sent out to beta readers. They are given two weeks to read, comment, and return it.
Combining the versions the readers send back takes approximately 4 hours.
The third draft takes about 14 8-hour days, times two authors, for approximately 224 hours.
Formatting the manuscript for ebook for the final edit takes about 5 hours.
The final edit takes about seven 8-hour days, for approximately 56 hours.
Making the final corrections in the manuscript takes between 2 and 3 8-hour days, for approximately 16 to 24 hours.
Creating the cover and adapting it for both print and ebook takes about 8 hours.
Formatting the finished manuscript for print takes 8 hours.
Formatting the finished manuscript for ebook takes 8 hours.
Writing a new web page and updating existing webpages to accommodate the new book takes about 3 hours.
Uploading the new webpages to my site and the book files to Amazon, Barnes & Noble, Smashwords, and Createspace takes about 4 hours.
Writing the blog post to announce the new book takes about an hour.
Posting the blog post and linking it to social media sites takes about an hour.

Total time: Somewhere between 1110 and 1278 hours.

If I was working a "desk job", the 9-5 = 8 hours, minus 30 min lunch and two 15 min "coffee" breaks, would be 7 hours work time per day.

1110 hours = 158.5 days, or 31 weeks, or 7 3/4 months.

1278 hours = 182.5 days, or 36 1/2 weeks, or nine months.

It takes most people one to three days to read my book.

No wonder authors compare the publishing process with sending a child out into the world. Keep in mind this process would take as much as two extra years if I had a publisher and an agent involved in the process.

Going back to the hypothetical desk job: if I made $10/hour, I would earn $1600 per month, or $14,400 in nine months. At a royalty rate that pays me approximately $2 per book, I have to sell 7,200 books to make an average of $10/hour over the nine months it took me (without salary) to create the book.