πͺ΅ Firewood Cord Calculator
Convert your stack into cords, face cords, and heat output.
Full Cords
How to Use This Calculator
Measure your stacked firewood in feet, enter the three dimensions, and the calculator converts the stack to full cords and face cords, then estimates the heat energy for common wood types.
Measure the Stack Length along the ground in feet. A standard stack is 8 feet long.
Measure the Stack Height in feet, from the ground to the top of the pile. Measure in a few spots and average them, since stacks settle unevenly.
Measure the Stack Depth in feet. Four feet deep is a full cord stack; a single row of 16-inch pieces is about 1.33 feet, which is a face cord.
Read the results: total cubic feet, full cords (128 cu ft each), face cords (42.7 cu ft each), and the estimated BTU heat content for oak, maple, and pine.
Cord Math and BTU Table
Heat content per cord (seasoned, 20 percent moisture): oak 24 million BTU, maple 19 million BTU, pine 14 million BTU. These are stacked-cord figures that account for the air gaps between pieces. Real-world heat into the house also depends on stove efficiency: a modern EPA stove delivers 65 to 75 percent of the wood's energy to the room, while an open fireplace delivers only 10 to 15 percent. Multiply the BTU totals below by your stove's efficiency for the heat you will actually feel.
Worked Example
A classic full cord stack measures 8 feet long, 4 feet high, and 4 feet deep. Cubic feet = 8 x 4 x 4 = 128 cubic feet. Full cords = 128 / 128 = 1.0 cord. Face cords = 128 / 42.7 = 3.0 face cords. Heat: oak = 1.0 x 24 million = 24 million BTU; maple = 19 million BTU; pine = 14 million BTU. A smaller stack of 8 x 4 x 2 feet = 64 cubic feet = 0.5 cords, or about 1.5 face cords, holding 12 million BTU of oak. In a stove running at 70 percent efficiency, that full oak cord puts roughly 16.8 million BTU of heat into the home.
Practical Firewood Tips
Stack wood bark-side up on pallets or rails to keep it off the damp ground, and leave the sides open for airflow while covering just the top. Split pieces season faster than rounds: split anything over 6 inches in diameter. Buy firewood in spring when prices dip and you have all summer to season it yourself. When buying by the face cord, confirm the piece length in writing, since a face cord of 12-inch pieces holds 25 percent less wood than one of 16-inch pieces. Never burn pressure-treated lumber, painted wood, or plywood: the chemicals in them are toxic and corrode the chimney.
Frequently Asked Questions
How big is a cord of firewood?
A full cord is 128 cubic feet of stacked wood, traditionally piled 8 feet long, 4 feet high, and 4 feet deep. A face cord (also called a rick) is a single row of that stack: 8 feet long, 4 feet high, and 16 inches deep, which equals one third of a full cord, or about 42.7 cubic feet.
What is the difference between a full cord and a face cord?
A full cord is the legal measure in most states: 128 cubic feet. A face cord is one row deep of a full cord stack (usually 16 inches, the length of a firewood piece), so it takes three face cords to make one full cord. Face cords are common for casual sellers; always ask for the piece length so you know what fraction of a cord you are getting.
Which firewood has the most BTU per cord?
Dense hardwoods lead the pack. White oak delivers about 24 million BTU per cord, sugar maple about 19 million, and pine only about 14 million. That means a cord of oak holds roughly 70 percent more heat than a cord of pine, so the cheaper softwood is rarely the better value per unit of heat.
How many cords do I need for a winter?
A typical US home with a modern wood stove burns 3 to 5 cords per winter in a cold climate (think upper Midwest or New England), and 1 to 2 cords in milder regions. Poorly insulated homes and open fireplaces use more. Multiply your daily burn by about 150 heating days to estimate your own number.
Does firewood need to be seasoned before burning?
Yes. Fresh-cut wood can be 50 percent water by weight and burns poorly, smokes heavily, and coats the chimney with creosote. Season split firewood for 6 to 12 months (oak needs the full year) until the moisture content drops below 20 percent, which you can check with a cheap moisture meter.