Is it legal to convert a book I own a hard copy of to a format I can view on my kindle?

I don't really have any interest in buying multiple copies of books I own, but I would like to have some of the books I already own on my kindle for reading when I'm not at home, it's easier than carrying a bunch of hard copies around. I saw some stories where people lost their kindle accounts for "violations of terms of service". I can't really find anything on the legality of the issue. I don't have a scanner, so I don't want to bother typing out a 1,000 page book in Word, then converting it to a kindle file if it's just going to get my account revoked.