A farmer has been defined by the gov. as one acre , a mule, and an a milk cow. A hog an chicken. And at that time they said that one acre would produce food for a family of four and your livestock. In the 70s the gov. move that from a acre to ten acres. I would say a farmer is any one in agriculture, from truck farming to any size you can grow to. Below a truck farmer, is a garden. I file my tax as a small farmer, because that-bracket the gov. Do not require you to make a profit. As a hobby farmer they do. Lots of large horse farm or filing there tax as a hobby farm, any are making big money. Go line and you can see the different in farm tax filing.