How big is 40 acres of land?

My dream is to have a bunch of land in Wyoming, where I can ride a horse all over the place and still be on my own land. I've seen 40-acre plots of land advertised for sale, and I'm wondering if that would be the right size for me. I don't have money to buy any land now, but I want to know for future... show more My dream is to have a bunch of land in Wyoming, where I can ride a horse all over the place and still be on my own land. I've seen 40-acre plots of land advertised for sale, and I'm wondering if that would be the right size for me. I don't have money to buy any land now, but I want to know for future reference so I can have some idea of how much money I'd need to save up for a down payment (that is, I want to know whether I need to save up money for more than one 40-acre plot).
Update: I have an idea of how big one acre is, because I've lived on 1-2 acres of land. What I want is a better idea of exactly how big 40 acres is. For example, if it's a square, how many miles long would it be on each side? I'm just trying to get a good picture in my head.
3 answers 3