Firewood Cord Calculator

How many cords of firewood do I need for the winter?

Divide the heat your home needs for the winter by the heat one cord delivers: for a 1,800 ft² home in a cold climate with average insulation, heated entirely by an EPA-certified stove burning red oak, that is 43.4 million Btu ÷ 19.6 million Btu, or about 2.25 cords (a likely range of 1.75 to 2.75). At the $360 per cord this page’s face-cord example implies, that is about $810. The winter firewood estimator above runs the same math for your own home, climate, stove, and wood.

The estimator is an energy balance, not a rule of thumb. The heat a home needs comes from the U.S. Energy Information Administration’s 2020 Residential Energy Consumption Survey: space-heating energy divided by heated floor area for homes in each climate zone, converted from fuel burned to heat delivered. That works out to about 7 kBtu per square foot a year in the mildest zone and 24 in the cold zone. A cord’s heat comes from the species’ density, the 80–85 ft³ of solid wood Oregon State Extension counts in a stacked cord, and about 8,500 Btu per dry pound (USDA Forest Products Laboratory), which leaves 6,800 Btu per pound at 20% moisture. The stove then decides how much of that reaches the room: EPA reports an average efficiency of 71% for certified non-catalytic stoves.

Cords for one winter, for a 1,800 ft² home with average insulation heated entirely with red oak. Four things move the number. The stove: an older 40%-efficient stove burns 1.8× the wood of a certified one for the same heat. The climate: the cold zone needs 1.5× the heat of the moderate zone per square foot. The house: in the Midwest data, homes built before 1960 used 1.33× the average heating energy per square foot and homes built since 2000 used 0.66×. And the wood: a cord of eastern white pine delivers only 57% of the heat of a cord of red oak (1.8× as many cords for the same heat).

Check it against real wood burners. EIA’s survey found that US homes heated mainly with wood burned about 85.0 million Btu of wood a year, which at the survey’s 20 million Btu per cord is 4.25 cords, and Kentucky Extension’s “middle of the road” figure is 3.5. Wood use in the survey runs highest in older and rural homes, and Illinois Extension notes that published stove efficiencies are optimum-performance figures that fall when a stove is run or maintained poorly. Run the same reference home through an older stove and the estimate is 4 cords, close to the survey average. Buy dry wood, 20% moisture or less: wetter wood delivers less heat than this math assumes.

The math, honestly simple

Stack volume is length × height × depth; divide by 128 ft³ and you have cords. The value of this tool isn’t the arithmetic — it’s the unit conversion defense. Sellers quote face cords, ricks, racks, and truckloads; only the cord has a legal definition. Convert everything to dollars per cord and the market gets honest fast. Volume is only half the story, though: a cord of dense oak packs substantially more wood — and so more heat — than a cord of light pine, and weighs more too — the wood weight calculator shows the species-by-species difference, green or seasoned, before you commit a truck to hauling it.

What is a cord of firewood?

A cord of firewood is 128 cubic feet of wood stacked tightly — the classic 4 ft high × 4 ft deep × 8 ft long pile, or any other stack whose length × height × depth multiplies out to 128 ft³ (about 3.62 m³).

It is also the legal unit. The model regulation in NIST Handbook 130 (Uniform Regulation for the Method of Sale of Commodities, Section 2.4) defines a cord as 128 ft³ of wood that is “ranked and well stowed”: pieces in a row, touching and parallel, stacked compactly. Outside a few exceptions such as small packaged bundles, it says firewood is to be sold by the cord, a fraction of a cord, or the cubic meter, and it bans “face cord,” “rack,” “pile,” and “truckload” — or terms of similar import — in advertising and sales.

Handbook 130 is a model: each state decides whether to adopt it and in what form, so the rules that bind your seller come from your state weights-and-measures office. The practical rule is the same everywhere. A cord is a volume you can measure, and a rick, a fireplace cord, or “a truckload” is just the seller’s label until you have the dimensions. And a cord measures stack space, not wood: even a tight one holds only about 80–85 ft³ of solid wood, as the measuring steps below explain.

Face cord, rick, fireplace cord, truckload — how many cords?

A face cord is 1/3 of a cord when the logs are 16 inches long — 1/4 at 12 inches, 1/2 at 24. It is a 4 ft × 8 ft face of stacked wood one log deep, so its volume is 32 ft² times the log length, and dividing by 128 gives cords. The table runs that math for common log lengths.

“Rick” is informal too. Illinois Extension puts a rick at one-third of a cord for 16″ pieces — the same size as a 16″ face cord — and says face-cord depth runs anywhere from 12 to 18 inches, so the deeper of two “face cords” can hold 50% more wood than the shallower one. “Fireplace cord” is not a defined unit either: ask for the face height and length plus the log length, then run them through the calculator above.

A truckload is the loosest number in the table. Illinois Extension says a full-size pickup with an 8 ft bed holds roughly 1/3 to 1/2 cord depending on how it is loaded — about 43–64 ft³ of stack. Treat that as an estimate, and measure after stacking.

How to measure a stack of firewood

Measure the stack’s length, height, and depth in feet, multiply them for cubic feet, then divide by 128 — that is your cord count.

1. Stack it first. Rank the wood in tight, parallel rows with the pieces touching — the legal definition assumes wood that is “ranked and well stowed,” and a loose pile can’t be measured honestly.
2. Measure three dimensions. Length along the row, height from the ground to the top of the stack (average it if the top is uneven), and depth. For a single row, depth is the log length; for two rows side by side, add both.
3. Convert inches to feet by dividing by 12. Sixteen-inch logs are 16/12 ft, or about 1.33 ft.
4. Multiply for cubic feet. 12 ft × 5 ft × 16/12 ft = 80 ft³.
5. Divide by 128. 80 ÷ 128 = 0.625 cord. In meters, divide m³ by 3.62. To price it, divide the asking price by the cords.

Mind what the number means. A cord counts stack space, not wood: Oregon State University Extension puts a tightly stacked cord at about 80 to 85 ft³ of solid wood — roughly 63–66% of the 128 ft³ — with the rest air between the pieces. Anything looser holds less: a USDA Forest Service study of stacked 4-foot pulpwood found that piece size, crookedness, and — most of all — how neatly the pile was built changed the solid content, with haphazard piles holding appreciably less. If you think in lumber terms, that solid wood is roughly 960–1,020 board feet of volume (one board foot is 1/12 ft³); the board foot calculator does that conversion for sawn stock.

How much does a cord of firewood weigh?

A tightly stacked cord of common firewood species weighs roughly 2,000–4,350 lb, from a light softwood like eastern white pine to a dense hardwood like shagbark hickory. Density is what moves the number. Each figure below is the species’ density at 12% moisture — the USDA Forest Products Laboratory data behind our wood weight calculator — times 80–85 ft³ of solid wood per cord, rounded to the nearest 50 lb.

The spread is wide: the same 128 ft³ stack weighs about 2.0× as much in shagbark hickory as in eastern white pine. At the heavy end that is up to about 2.2 tons of wood, which makes hauling a payload question for your truck and trailer, not just a stacking one.

Firewood seasoned to about 20% moisture — the level Illinois Extension recommends, “20 percent or less” — weighs somewhat more than these 12% figures, and green wood far more, so treat the table as a guide to how species compare rather than a scale reading.

Buying tips that pay for themselves

• Price the volume, not the pile. Enter the asking price above and compare $/cord across sellers.
• Log length changes face-cord value. 12″ logs make a face cord worth 1/4 of a cord; 24″ logs make it 1/2.
• Check moisture. A $50-cheaper green cord costs you a season of drying time.