I only glanced at the responses so forgive me for repeating things.
The acreage will depend on your state and the rules they have. I was always told the general rule of thumb is 3 acres for the first horse and then 1 for each additional horse so 2 horses would need 4 acres of pasture. I also know that if you have a barn where you can actually stall your horses and then you have paddocks for turn out the rules can change and you can actually get away with less acreage. Of course you are more than likely going to end up with dry lots if you have too many horses on too few acres.
The acreage will depend on your state and the rules they have. I was always told the general rule of thumb is 3 acres for the first horse and then 1 for each additional horse so 2 horses would need 4 acres of pasture. I also know that if you have a barn where you can actually stall your horses and then you have paddocks for turn out the rules can change and you can actually get away with less acreage. Of course you are more than likely going to end up with dry lots if you have too many horses on too few acres.