Running out of firewood in February is one of those situations that feels like bad luck but almost never is. It is almost always a planning problem, usually compounded by burning wetter wood than you should be, running a stove that is less efficient than you assume, and starting the season with less wood than you counted.
Here is the actual math, explained plainly, so you can do it for your situation and stop guessing.
What a Cord Actually Is
A full cord of firewood is a stack measuring 4 feet wide by 4 feet tall by 8 feet long, which works out to 128 cubic feet of total space. That total includes the wood itself and the air between the pieces. Depending on how tightly the wood is split and stacked, the actual solid wood in a full cord is somewhere between 70 and 90 cubic feet.
A face cord, also called a rick in some parts of the country, is one third of a full cord. It is 4 feet tall by 8 feet long but only as deep as the length of the individual pieces, typically 16 inches. When someone advertises firewood by the rick or face cord, make sure you know what length they are cutting before you buy. A face cord of 24-inch pieces contains more wood than a face cord of 12-inch pieces. The math matters when you are buying heat.
When doing any of the calculations below, use full cord as your unit. If you are purchasing face cords, convert first.
The Four Variables That Determine Your Number
Every honest answer to the question of how much firewood you need runs through the same four variables. Get these right and your estimate will be accurate. Skip any of them and you will be guessing.
1. Climate zone. How many heating days your location sees is the single biggest driver of firewood consumption. A home in northern Wisconsin running its stove from October through April faces a fundamentally different heating challenge than the same home in Tennessee. Cold-climate locations in the northern Midwest and Northeast, where heating seasons run five to seven months with regular extended cold snaps, require significantly more wood than moderate-climate locations.
2. Home size and insulation. Larger homes require more BTUs to maintain temperature. So do drafty homes with poor insulation, older windows, and gaps in the envelope. A modern well-insulated home of 1,500 square feet and a drafty farmhouse of the same square footage can have very different firewood needs depending on how well the house holds heat.
3. Species. Different wood species contain different amounts of energy per cord. A cord of white oak delivers roughly 24 million BTUs of potential heat energy. A cord of basswood delivers around 14 million BTUs. If you are burning basswood to heat a home that needs 24 million BTUs of usable heat per season, you will need nearly twice as many cords as a neighbor burning white oak. Species matter and the difference is not marginal.
4. Stove efficiency. Wood stoves and fireplaces do not deliver 100 percent of the BTUs in a log to your living space. An open masonry fireplace is roughly 10 to 20 percent efficient, meaning 80 to 90 percent of the heat goes up the chimney. An older wood stove that predates EPA efficiency standards might run 50 to 60 percent efficient. A modern EPA-certified wood stove can reach 70 to 80 percent efficiency. The difference between a 20 percent efficient fireplace and a 75 percent efficient stove, on the same amount of wood, is enormous. If you are running an older stove or a fireplace as your primary heat source, budget significantly more wood than the baseline estimates below.
The Baseline Numbers
These figures come from consistent reporting across university extension services, the USDA Forest Products Laboratory, and the experience of people who have heated with wood long enough to have accurate numbers.
For a primary wood heat installation in a cold climate, with a reasonably efficient modern stove and adequate home insulation, the general baseline is 2 to 3 full cords per 1,000 square feet of heated space per season.
Working through some common scenarios using that baseline:
A 1,000 square foot house in northern Wisconsin, well-insulated, running a modern stove as the primary heat source: plan for 2 to 3 cords of good hardwood.
A 1,500 square foot house under the same conditions: 3 to 4.5 cords.
A 2,000 square foot house: 4 to 6 cords.
These numbers assume you are burning seasoned hardwood in a reasonably efficient stove. Adjust upward if your home is poorly insulated, if you are running an older less efficient stove, or if your winters are longer and colder than average. Adjust downward if you have a modern high-efficiency stove, excellent insulation, and milder winters, or if wood is supplemental rather than primary heat.
If wood is supplemental to another heat source, meaning you run the stove regularly but it is not carrying the full load, 1 to 2 cords covers most situations. If wood is occasional, meaning fires a few times a week for ambiance and some warmth, a single cord typically gets you through a season.
The BTU Method for Precision
If you want a more precise number than the square footage baseline, run the actual math. The formula is:
Annual BTUs needed divided by BTUs per cord of your wood species, divided by your stove efficiency as a decimal, equals cords required.
Getting each of those three numbers:
Annual BTUs needed. If you have been using natural gas or heating oil, your utility bills give you the answer directly. Natural gas is measured in CCF or therms. One CCF contains about 100,000 BTUs. One therm is 100,000 BTUs. Add up your annual gas usage in therms and you have your annual BTU requirement. If you are starting from scratch without a prior heating record, a rough estimate for a cold climate home is 50 BTUs per hour per square foot. For a 1,500 square foot home, that is 75,000 BTUs per hour during peak cold. Multiply by the number of heating hours in your season to get an annual figure.
BTUs per cord by species. These are well-established values measured and published by the USDA Forest Products Laboratory. A selection of common firewood species and their approximate BTU values per cord:
White oak: 24.2 million BTU Red oak: 22.1 million BTU Hickory: 24 to 25 million BTU Sugar maple: 25 million BTU Ash: 20 million BTU Birch: 18 to 20 million BTU Elm: 20 million BTU Basswood: 14 million BTU Softwoods like pine: 15 to 18 million BTU depending on species
If you burn a mix of species, estimate the proportion of each and weight the BTU value accordingly.
Stove efficiency. Check the manufacturer's specifications for your specific stove. EPA-certified stoves sold after 2015 typically run 70 to 80 percent efficient. Older non-certified stoves run lower, often 50 to 60 percent. Open fireplaces run 10 to 20 percent. Use the manufacturer's number if you have it. If you do not, use 60 percent for an older stove and 75 percent for a modern certified stove as reasonable working estimates.
Run those three numbers through the formula and you will have a more accurate cord estimate than any rule of thumb provides.
Why Your Estimate Should Include a Buffer
The baseline calculations above are starting points. The practical recommendation for anyone running wood as primary heat is to put up 10 to 25 percent more wood than your estimate says you need.
Winters vary. A colder-than-average February can add weeks to your heating season. Wet wood burns less efficiently than the BTU tables assume because energy goes toward boiling off moisture rather than heating your house. A stove running hotter than usual to make up for wet wood deposits more creosote and requires more cleaning. A cord of poorly seasoned wood is not a cord of properly seasoned wood in practice, even if it measures the same in the stack.
Put up more than you think you need. The worst outcome is that you enter next winter with surplus dry wood already in the pile, which is not a problem anyone complains about.
The Connection to Splitting and Planning
The cord count determines how much work your splitting season needs to accomplish. If you need 4 cords of seasoned hardwood for next winter, and seasoning properly takes 6 to 12 months for most species and up to 18 to 24 months for dense hardwoods like white oak, then you need to have 4 cords split and stacked by the end of this spring at the latest.
That is the planning loop that serious wood heat operators run every year. Figure out how much you need. Get that amount cut, split, and stacked in time to season properly. Burn it the following winter while putting up the next batch.
The tools that make the splitting side of that loop manageable are covered in our splitting axe vs. maul guide. The seasoning side, how long different species actually take and how to stack for maximum airflow, is covered in the firewood seasoning guide.
FAQ: How Many Cords of Firewood Do You Need
What is a full cord of firewood? A full cord of firewood is a stack measuring 4 feet wide, 4 feet tall, and 8 feet long, totaling 128 cubic feet of volume. That volume includes both the wood and the air spaces between pieces. The actual solid wood in a full cord is typically between 70 and 90 cubic feet depending on piece size and how tightly the wood is stacked.
How many cords of firewood does a 1,500 square foot house need? In a cold climate like the northern Midwest or Northeast, with a reasonably efficient wood stove as the primary heat source and average insulation, a 1,500 square foot home typically burns 3 to 4.5 full cords of seasoned hardwood per season. That range shifts based on stove efficiency, insulation quality, how cold your winters run, and what species you are burning.
Does wood species affect how many cords you need? Significantly. A cord of white oak delivers roughly 24 million BTUs of potential heat energy. A cord of basswood delivers around 14 million. If your heating requirement stays constant, you need nearly twice as many cords of basswood to produce the same amount of usable heat as white oak. Dense hardwoods like oak, hickory, and maple deliver more heat per cord than lighter hardwoods or softwoods.
How does stove efficiency affect firewood consumption? A wood stove operating at 75 percent efficiency delivers three times as much usable heat from the same log as an open fireplace running at 25 percent efficiency. Stove efficiency is one of the most significant variables in firewood planning and one of the most commonly overlooked. If you are running an older stove or a masonry fireplace as primary heat, budget considerably more wood than the standard guidelines suggest.
Should I buy more firewood than my calculation says I need? Yes. The standard recommendation is to put up 10 to 25 percent more than your estimate. Winters vary, wood moisture content varies, stove performance varies, and running short in mid-January is a worse outcome than having surplus dry wood going into the following winter.
Know Your Number Before the Season Starts
The guy who runs out of firewood in February did not have a weather problem. He had a math problem that started the previous spring when he did not put up enough wood.
Figure out your number. Run the baseline calculation using your square footage and climate, or work through the BTU formula if you want precision. Add a buffer. Get that wood cut, split, and stacked in time to season properly.
The Council Tool splitting mauls and axes are built for the splitting side of this operation. American-made, properly forged, and priced for someone who actually uses the things.
Know your number. Stack it early. Heat well.