How many acres of wood lot are needed to heat a house?

Besides length and severity of winter.
Home Design will Factor.Size,Solar gain and as others have said Insulation.Wind Breaks also come into play.
The other big Factor is type of Stove. Some are Very efficient,Such as a masonry stove/Russian Furnace. Others such a Franklin not nearly as Efficient.
Then there is Growth Season and Method of harvest.

Its not nearly as cut and dry as you would think.

You can burn pine,if anything it burns Hotter. Hotter a fire burns the faster it Burns.The only thing with pine is you need to clean you flue more often because it does build up tar and creosote faster.

Dad & uncle cut wood for 3 houses from 20 acre woodlot.

I manage my 2 acre grove, plus random trees around the farm perhaps another 2 acre's worth for the house - before the boiler busted - and it worked out.

I'd say the cord per acre per year thing would be about right. Probably need 5 acres here where I am if you want 100% heat - then do you want to feed the small stove in the shop, etc?

--->Paul