What Is a Cord of Wood?
A cord is the legally recognized unit for measuring stacked firewood in the United States and Canada. By definition, one cord equals 128 cubic feet of wood, traditionally arranged as a stack 4 feet wide, 4 feet high, and 8 feet long. The term dates back to the 1600s when firewood was measured using a physical cord or rope of standard length. Today, most states have laws that define a cord precisely and require sellers to price firewood by this unit to prevent fraud.
The 128 cubic foot figure includes both the solid wood and the air space between stacked pieces. If you were to submerge a cord of hardwood and measure only the actual wood volume (no air gaps), you would get roughly 80 to 90 cubic feet of solid material depending on how tightly it was stacked and how straight the logs are. This distinction matters because two stacks with identical exterior dimensions can hold different amounts of actual firewood based on stacking quality.
Related measurements include the face cord (one-third of a full cord when wood is cut to 16-inch lengths), the rick (a regional term often synonymous with face cord), and the thrown cord or loose thrown cord, which accounts for about 180 cubic feet of loosely piled wood. When ordering from a supplier, confirm which unit they are pricing so you can compare accurately using this calculator.
How Cord Volume Is Measured
The calculator uses the straightforward formula: length x height x depth divided by 128. This gives you the number of standard cords in your stack. For example, a stack 8 feet long, 4 feet high, and 4 feet deep equals 128 cubic feet, which is exactly 1.0 cords. A stack 12 feet long, 4 feet high, and 2 feet deep (a typical two-row deep configuration of 16-inch pieces) equals 96 cubic feet, or 0.75 cords.
Accuracy depends on measuring the actual stack dimensions rather than the pile footprint. If wood is stacked against a wall, measure from the wall to the front face of the stack. For freestanding stacks, measure the full footprint. Irregular stacks should be measured at several points along the length and height, then averaged for a reasonable estimate. Minor variations of plus or minus 5 percent are normal in field conditions.
For construction projects that require dimensional lumber rather than firewood, the lumber calculator handles board footage and linear feet conversions. When you need to estimate the weight of a single log before splitting, the log weight calculator factors in species and moisture content to give you pound estimates per log.
Understanding Wood Types and Heat Output
Not all firewood delivers the same heat. The BTU content per cord varies dramatically between species due to differences in wood density. Oak and hickory, the densest common firewoods in North America, produce approximately 26 million BTU per cord. Maple and birch fall slightly lower at 24 million BTU. Softwoods like pine and cedar deliver about 17 million BTU per cord, while spruce and fir produce around 16 million BTU. These numbers come from extensive USDA Forest Products Laboratory testing.
The practical difference is substantial. If your home needs 60 million BTU to stay warm through winter, you would burn roughly 2.3 cords of oak or 3.5 cords of pine. Softwoods also burn faster and produce more creosote, meaning more frequent refueling and chimney cleaning. Most experienced wood burners prefer dense hardwoods for overnight burns and reserve softwood for kindling or shoulder-season heating.
If you work with milled lumber and need weight estimates for transport or structural planning, the lumber weight calculator covers dimensional lumber across species and moisture levels. For converting raw timber to board feet for milling, the board foot calculator handles the geometry of round logs to usable lumber.
Stacking Methods That Affect Volume
How you stack firewood changes the actual wood volume within a given footprint. Tight stacking — where split pieces are placed parallel and close together — can fit 90-plus cubic feet of solid wood into a 128 cubic foot cord. Loose stacking with crossed or randomly oriented pieces might only deliver 70 cubic feet of actual wood in the same space. Over time, settling reduces volume as pieces shift and compress under their own weight.
The orientation of splits matters too. Rounds (unsplit sections) waste space because their circular cross-sections create large air pockets. Split pieces with flat faces stack more efficiently. Most sellers stack fairly tight to maximize apparent volume, while buyers benefit from restacking loosely for better drying airflow. This is why two people can look at the same pile and disagree about whether it truly measures a full cord.
For landscaping projects that also involve bulk materials alongside firewood storage, the mulch calculator estimates cubic yard coverage for garden beds, while the gravel calculator handles base material for constructing a stable firewood pad or storage area.
Seasoning and Moisture Content
Freshly cut (green) firewood can contain 50 percent or more water by weight. Seasoned firewood — dried for at least 6 to 12 months under cover — should read below 20 percent moisture on a meter. The drying process is critical because wet wood wastes heat energy evaporating water instead of warming your home. Green oak can lose 20 percent of its heating value compared to seasoned oak of the same volume.
Splitting wood accelerates drying by increasing surface area. Stacking in single rows with sun exposure and airflow through the pile reduces seasoning time. Covering only the top of the stack (not the sides) prevents rain soaking while still allowing cross-ventilation. Firewood stacked in damp or shaded conditions may take two full seasons to properly dry, especially dense hardwoods like oak that naturally resist moisture release.
Wood ash from clean, seasoned hardwood makes a useful soil amendment. For calculating compost or soil additive quantities for your garden, the compost calculator handles volume and coverage estimates for incorporating ash and organic matter into planting beds.
Buying Firewood by the Cord
Firewood pricing varies widely across regions and seasons. In the northeastern United States, a cord of seasoned hardwood typically runs $250 to $400 delivered. In the Pacific Northwest, softwood cords sell for $150 to $250. Prices spike during cold snaps and fuel shortages, so buying early — in spring or summer — often saves 15 to 25 percent. Always ask whether quoted prices include delivery and stacking, as these services add $50 to $100 per cord.
Verify the quantity you receive. When a delivery arrives, measure the stack before the seller leaves. A standard delivery truck (pickup with an 8-foot bed) holds roughly half a cord if stacked to cab height. Dump trucks and trailers vary widely. Use this calculator with your measured dimensions to confirm the delivery matches what you paid for. If a seller quotes by weight (ton or pound), ask for the moisture content to estimate actual wood volume — green wood weighs significantly more than seasoned wood.
State weights and measures offices regulate firewood sales in most jurisdictions. If you receive less than the contracted amount, you can file a complaint. Documentation helps: photograph the delivered pile, measure it, and keep your order receipt. Honest sellers expect verification and will not object to you checking dimensions.
Estimating Heating Value for Your Home
To estimate how much firewood you need, start with your home's heat loss. A well-insulated 2,000-square-foot home in a cold climate (6,000 heating degree days) typically needs 50 to 80 million BTU per heating season. Dividing by the BTU content of your chosen wood gives a rough cord requirement: 2 to 3 cords of oak, or 3 to 5 cords of pine. Older, poorly insulated homes may need 50 percent more.
Stove efficiency also affects consumption. Modern EPA-certified wood stoves operate at 60 to 80 percent efficiency, meaning 20 to 40 percent of the fuel's heat energy goes up the chimney. Older non-certified stoves may only deliver 40 to 50 percent efficiency. Outdoor wood boilers are typically less efficient still, requiring 30 to 50 percent more wood for the same heat output. Factor this into your fuel budget when using the BTU estimates from this calculator.
Structural considerations also matter for homes heated with wood. If you are building or renovating and need to verify that beams supporting a heavy masonry chimney or wood storage area are adequate, the wood beam span calculator provides load and span estimates for common dimensional lumber sizes.
Common Cord Wood Mistakes to Avoid
The most frequent mistake is confusing face cords with full cords. A seller quoting $75 per face cord sounds cheaper than one quoting $225 per full cord — but they are the same price for the same volume of 16-inch wood. Always convert to full cord equivalents before comparing prices. This calculator makes that conversion automatic when you enter the actual stack dimensions.
Another common error is ignoring moisture content. Green wood priced at a discount often costs more per usable BTU than seasoned wood at full price, because a significant portion of the energy goes toward drying the wood in your stove. Wet wood also produces excessive smoke, builds creosote in your chimney (a leading cause of chimney fires), and leaves behind more ash. A $20 moisture meter pays for itself quickly when buying firewood.
Finally, many buyers underestimate how much space a winter's worth of firewood requires. Four cords of 16-inch wood stacked four feet high spans about 32 feet in length. Measure your storage area before ordering, and plan for enough covered space to keep the wood dry through snow and rain season. Building a simple lean-to or three-sided shed with a sloped roof is one of the highest-return DIY projects for rural and suburban homeowners who heat with wood.