Totally agree Sniper. But the amount of land you grow on will depend a lot on how many is eating out of it. If your growing food on three acres (assuming just average land) you can feed a good crowd of people. Now this is assuming no animals, or at least nothing more than chickens or ducks, are raised on it. Cattle can require an acre per head on average land and 25-50" of rain per year. But just looking at crops on three acres, your going to have help keeping it worked, while others are gather wood, water, security, what ever else might be needed. Feeding 2 people could be grown on 1/2 acre easily enough.
Keep in mind though that you need to leave ground fallow every few years and keep cover crops going to replenish the nutrients in the soil. Right now I try and do a 3 year rotation. I also grow cover crops at least every winter in most years. This is where animals would help. Manure is very benificial. Leaves from trees are another.