Cord of Wood Calculator

A face cord is not a size

A cord is 128 cubic feet: a stack four feet high, four feet deep and eight feet long. It is defined in law across most of North America, and it is the only firewood measure that is.

A face cord — also called a rick or a rank — is a stack four feet high and eight feet long, and however deep the logs happen to be. So its size depends entirely on the log length, and it is not a quantity until someone says what that is.

Paying a cord price for a face cord of 12-inch logs means receiving a quarter of what was paid for. The seller may not have intended to mislead — “cord” is used loosely in conversation, and a stack four by eight does look like a lot of wood.

This is why NIST’s model regulation, adopted in most US states, permits firewood to be advertised and sold only by the cord or a fraction of a cord. Terms like face cord, rick, rank, truckload and pile have no legal standing precisely because they mean different things to different people.

The calculator refuses to convert a face cord without a log length, rather than picking a common one. Sixteen inches is the usual answer and giving it as a default would be a plausible number that is wrong a third of the time.

A cord is stacked, not solid

The 128 cubic feet includes the gaps. A cord is a measure of a stack, and a stack of split logs is somewhere between 70 and 85 per cent wood depending on how straight the pieces are and how carefully they were laid.

So a cord of oak at a realistic packing holds about 2.9 m³ of actual wood and roughly 2.2 tonnes of it. Assuming the full 3.62 m³ were solid overstates the mass by a quarter — and that is before any question of species or moisture.

The practical consequences run in both directions. A delivery tipped loose into a pile occupies noticeably more space than the same wood neatly stacked, which is why sellers who deliver loose and buyers who measure stacked disagree. And short, crooked or unsplit pieces stack worse, so a cord of them contains less wood than a cord of clean straight splits at the same nominal volume.

The metric measure has the same property. A stere is one cubic metre of stacked wood — 0.276 of a cord — and it too counts the air. Some European trade quotes solid cubic metres instead, which is a different quantity again, so the word to look for is whether the volume is stacked or solid.

Volume bought, mass burned

Firewood is sold by volume and burns by mass, and the two are related by density — which varies nearly two to one between common species.

Nearly twice the heat from the same volume. What makes this counter-intuitive is that oven-dry wood is about 20 MJ per kilogram whatever the species — the chemistry barely varies. All the difference is in how much wood fits into a cord.

Which means a cord of hickory and a cord of poplar are not comparable purchases at the same price, and two identical-looking deliveries can last very different lengths of time with no one having misrepresented anything.

Softwoods carry a reputation for burning badly that is mostly about density and resin rather than about being unsuitable. Well-seasoned pine burns cleanly and gives good heat; there is simply less of it in a cord, and it burns faster, so it needs feeding more often.

Green wood loses twice

Freshly cut wood is around half water by weight, and that costs energy in two separate ways — which is why the penalty is larger than people expect.

First, the water is not fuel. Half the weight of a green log contributes nothing at all. Second, boiling it off consumes heat the fire would otherwise have delivered — about 2.26 MJ for every kilogram of water evaporated.

Green wood delivers 43% less usable energy per kilogram than seasoned, and the loss is not the whole story. A fire burning wet wood runs cooler, so it burns less completely — producing more smoke, more creosote in the flue, and a real chimney fire risk over a season.

Seasoning takes time that cannot be shortened much: six months for softwoods and split ash, a year for most hardwoods, and two for oak. It needs the wood split, stacked off the ground and covered on top but open at the sides. A moisture meter on a freshly split face costs very little and settles the question.

So buying green wood cheaply and burning it the same winter is the most expensive way to heat with wood: less heat per kilogram, more of it needed, and a flue that needs sweeping sooner.

Buying without being caught

Four questions cover nearly everything, and all of them are worth asking before the wood arrives rather than after.

What are the stacked dimensions? Not “a cord” or “a truckload” — the height, the length and the log length. A full cord is 4 × 4 × 8 feet however it is arranged; anything else needs its dimensions to mean anything.

What species? Mixed hardwood is a legitimate answer and it is also the answer that hides poplar. If the price is a hardwood price, the mix is worth asking about.

How long has it been split and stacked? Cut and split are different dates, and only the second one starts the seasoning clock properly. “Seasoned” is not a defined term and is used loosely.

Will it be stacked or tipped? A tipped load cannot be measured against a cord until it is stacked, and by then the seller has gone. Stack it and measure it if the quantity matters.

One thing worth adding that the arithmetic cannot: the appliance matters as much as the wood. An open fire puts a small fraction of the fuel’s energy into the room and most of it up the chimney, while a modern closed stove delivers the large majority. The kilowatt hours on this page are the energy in the wood, not the heat that reaches you.

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Sources and methodology

The cord is defined in NIST Handbook 130 as 128 cubic feet of well-stacked wood, and the same model regulation is why most US states permit firewood to be sold only by the cord or a fraction of one — “face cord” and “rick” have no standing as units of sale. The heat figures are the Forest Products Laboratory ranges for seasoned wood, and the moisture treatment follows the gross-against-net calorific value distinction in ISO 18125.

• NIST Handbook 130 — Uniform Regulation for the Method of Sale of CommoditiesNational Institute of Standards and Technology · verified 2026-09-08 · The cord as 128 cubic feet of well-stacked wood and the model regulation that firewood be sold by the cord or fraction of a cord — the reason "face cord" and "rick" have no standing as units of sale in most US states
• Firewood heat values and characteristicsUSDA Forest Products Laboratory · verified 2026-09-08 · The published heat content per cord for seasoned species and the density figures behind them — the basis for the point that heat per cord tracks density rather than any difference in the wood’s chemistry
• ISO 18125 — Solid biofuels: determination of calorific valueInternational Organization for Standardization · verified 2026-09-08 · The distinction between gross and net calorific value and the treatment of moisture, which is why wet wood loses energy twice: the water is not fuel and vaporising it consumes part of the heat released