Like the man says: it depends. Where are you? What type of trees? Soils? You can go to the NRCS Soil Survey site and look up the potential yield for wood production in your area. Here I believe most people figure 1-1 1/2 loggers cord of wood per acre just trimming up dead and down in established Maple/oak forest. Back when it was cold some of us with old houses figured as much as 20 cord a winter. Winters are not as cold now so I get by with 3-5 cord with some propane. So how tight is your house, size, are you using something else all figures into it. I am kind of jumping around, but it all depends on these things. If I had to depend on lodgepole pine in the Bitterroot Mts. I doubt I would ever stop cutting. When I lived outside of Atlanta I didn't burn a cord, but then I just didn't feel as cold as the natives did. So maybe they burned more.