I buy shoes that are sized 11.5 (or sometimes 11), so either my shoe has lengthened with time and wear, or 11.5 is the internal dimension of the shoe, and that's how they sell shoes: by their internal dimension? I'll have to measure new shoes someday [Lol]
Anyway, my backyard lawn is almost exactly 1,300 square feet (or 1,305 by my best count). It's 83 feet by 18 feet, minus the patio. The yard itself is larger, but I've removed the square footage of the veggie garden, the patio, and the rock "mote" extending from the foundation of the house. Again I used shoe paces to measure, but I think it's fairly accurate. I guess a tape measure would be best. Oh well, when it's warmer...
I think the front lawn is about 1,950 square feet, and the two side lawns total about 650 square feet. So total lawn square footage is 3,900--we'll say 4,000 for easier remembering.
I don't mean to brag or anything. I'm sure some of you have an acre or more of lawn. I'm really posting this info for my future reference, in case I forget the footage, which is likely to happen soon.