Our square footage is about 1200. We're in the Mid-Atlantic (zone 6, I think), and the thermostat is set to 66 when we're home and 60 when we're away/asleep. I don't track our oil usage real closely, but it seems like we're getting a 100-150 gallon delivery every other month during the winter. I should note that we have a summer/winter boiler- that is, it supplies our hot water as well as our heat. So a monthly usage of 50-75 gallons includes hot water heating. Once the heat goes off in the spring, we might take a load every 4 months or so.