How do you guys estimate renovations?

Original post

I've always been off on how much something might cost. Either underestimated or overestimated the cost of things. Obviously, spending less than I wanted to is always a plus. I've renovated a kitchen before, and since I did most of the manual labor, it cost less, but the time it took was a ton. This time I want to switch out carpet for vinyl flooring, the floor isn't level, so there might be work needed to be done there. Also, I'm hiring someone so my time is less used.