How Much Wood Will a Wood Stove Burn in a Winter?

Cords and BTUs

• One cord of wood measures 8 feet long, 4 feet high and 4 feet wide, and fills about 128 cubic feet of space. A BTU (British Thermal Unit) is standard heat measurement. The BTU output varies for different types of wood because some wood species have higher moisture content than others. Even wood that is dried and seasoned still has moisture inside. Wood species including shagbark hickory, sugar maple and white oak are considered high output firewood species and produce up to 30 million BTUs of heat. Beech, Douglas fir and red elm are medium output firewood specie, with BTU ranges up to 24 million. And aspen, white pine and balsam fir are low output specie, and deliver from 12 to 17 million BTUs.

Wood for 500 Square Feet

• Since wood stoves are primarily used to heat a room or zone, imagine a 500-square-foot cabin to estimate the amount of wood that would be required. Assume that the cabin is in a cold climate area, such as Squaw Lake, Minnesota, where the winter temperature can range from minus 30 to minus 40 degrees Fahrenheit. It takes about 1.7 million BTUs to heat a 500-square-foot room each month in that climate. So, assume that the owner opts for firewood specie with a high output, such as beech wood, which has a BTU output of 23.6 million per cord. Also assume that the cost for a cord of beech wood is $250 and the heating season will run seven months, starting in October and ending in May, requiring about 12 million BTUs for the entire seven-month period. As a result, the owner would go though about a half of a cord of wood, at a cost of around $125 for the winter, averaging about $18 per month.

800 Square Feet

• Use the same location and specie of wood, but increase the size of the cabin to 800 square feet and estimate how much wood will be needed. This room would require about 2.7 million BTUs of heat each month, for about 19 million BTUs for the seven-month period. As a result, the owner would go though about 80 percent of a cord of wood, and do best by going ahead and purchasing a whole cord for $250 to ensure he doesn’t run out.

1,000 Square Feet

• A 1,000-square-foot space qualifies as “zone” heating, and may feature an open space floor plan with a large living room, kitchen and dining area. It would take about 3.5 million BTUs to heat 1,000 square feet each month, and about 25 million BTUs for the seven-month period. It would be best for this owner to purchase one and one-quarter cord of beech wood to ensure there was enough for the winter, at a cost of about $312, and averaging about $45 per month.