Article — Cord of Wood Calculator
Cord of wood calculator: how to measure a firewood stack
A full cord of wood is 128 cubic feet of stacked firewood, dimensioned 4 ft tall by 8 ft long by 4 ft deep. The definition is set by the US Department of Commerce and enforced state-by-state through weights and measures statutes. A face cord, sometimes called a rick, is the same height and length but only one log-length deep - typically 16 inches, or one-third of a full cord. The calculator above converts any rectangular stack into both units, plus weight and BTU output.
Most buyer-seller disputes around firewood come down to confused units. A "cord" advertised at half the going rate is almost always a face cord. The math below covers exactly what you are buying and what you should expect to burn through over a winter.
What a cord of wood is
The cord is a volume unit, not a weight unit. By federal definition (NIST Handbook 130) and most state weights-and-measures statutes, one cord equals 128 cubic feet of wood stacked compactly with the gaps between logs included in the measurement. The standard predates the United States - it was originally defined by an English statute in 1610, and the dimensions reflect what a single horse could reasonably haul.
About 90 cubic feet of that 128 is actually wood. The remaining ~38 cubic feet is air space between irregular logs. Tightly stacked, kiln-dried wood cut to uniform lengths can reach 95 cu ft of solid wood per cord. Loosely thrown cordwood (sometimes called a "thrown cord") can drop to 65 cu ft of solid wood for the same 128 cu ft envelope.
The Federal Trade Commission requires firewood to be sold by the cord or fractions of a cord. Phrases like "truckload," "face cord," or "rick" without a stated cubic-foot measurement are technically illegal in most US states, though enforcement is rare. When a seller refuses to quote in cords or cubic feet, that is the warning sign.
Cord of wood vs. face cord
This is where most disputes happen. A face cord is 4 ft tall by 8 ft long by one log-length deep. Log length is typically 16 inches (1.33 ft), producing a 42.7 cu ft stack - exactly one-third of a full cord. Longer logs (24 in or 2 ft) produce a face cord closer to half a full cord.
full cord = 4 x 4 x 8 ft = 128 cu ftface cord (16-in) = 4 x 8 x 1.33 ft = 42.7 cu ft = 0.33 cordface cord (24-in) = 4 x 8 x 2 ft = 64 cu ft = 0.5 cordrick = same as face cord (regional term)Regional terms muddle the picture. A "rick" is a face cord across the US Midwest. A "bush cord" is a Canadian variant equal to a full cord. A "thrown cord" can refer to loosely piled wood, often 25-30% less dense than a stacked cord. Ask for dimensions in feet rather than the seller's name.
How to measure a cord of wood
Measure the stack as it sits, not the logs inside. Length is the longest face, height is the tallest, depth is the distance from front face to back face. Stack the wood compactly with logs roughly parallel - loosely tossed piles measure larger than they should.
Take three measurements with a tape and multiply. A 4 ft by 4 ft by 16 ft stack is 256 cu ft, or exactly two cords. A 3 ft by 4 ft by 8 ft stack is 96 cu ft, or 0.75 cord. The calculator above also tracks face cords and weight, so you can compare what you measured to what you paid for.
Firewood BTU by species
Heat output varies by a factor of two between species. Dense hardwoods like hickory, oak, and hard maple deliver 24-28 million BTU per cord when fully seasoned. Softer hardwoods like cherry and birch fall in the 20-22 million range. Softwoods (pine, cedar, spruce) deliver 13-18 million BTU per cord.
- Hickory = 27.7M BTU/cord (highest)
- White oak = 26.4M BTU/cord
- Red oak = 24M BTU/cord (most common)
- Hard maple = 24M BTU/cord
- White ash = 23.6M BTU/cord (fast seasoning)
- Yellow birch = 21.8M BTU/cord
- Cherry = 20M BTU/cord (pleasant scent)
- Pine = 15.9M BTU/cord (kindling only)
- Cedar = 13M BTU/cord (sparks heavily)
The BTU values above come from the USDA Forest Products Laboratory and University of Maine Extension reference tables. They assume fully seasoned wood at ~20% moisture content. Burn the same wood at 50% moisture and you lose half the heat to evaporating water.
Seasoning firewood properly
Seasoning is the single biggest variable in firewood heat output. Green wood (freshly cut) holds 40-60% water by weight. Burning it wastes most of the energy as steam and creates creosote in the chimney. Properly seasoned wood holds 15-20% moisture and burns cleanly.
Stack split firewood off the ground (on pallets or rails), with the top covered against rain but the sides open to wind. Single-row stacks dry faster than dense piles. Plan on 12 months for split hardwood, 6-9 months for split softwood. A $20 pin-type moisture meter tells you exactly when wood is ready - under 20% is the target.
Splitting before seasoning matters more than people expect. A whole, unsplit log can take 3+ years to season. The same log split into quarters reaches 20% moisture in 9-12 months. Bark holds moisture, so splitting exposes more surface area and creates the channels for water to escape.
Cord of wood prices
US firewood prices vary substantially by region and species. Northeast and Great Lakes hardwood prices for the 2024-2025 season ran $250-400 per cord for oak or maple, delivered and stacked. Premium hickory or ash can reach $400-500. Mixed-species "stove wood" runs $200-300 per cord.
Buying off-season (April through August) typically saves 20-30%. Buying a whole tree-length log truck delivery (uncut, unsplit) saves another 30-40% but requires a chainsaw, a splitter, and labor. For homeowners with no equipment, prices roughly follow this seasonality: cheapest June, most expensive December-January.
Cords needed per winter
A typical well-insulated home using wood as the primary heat source burns 3-5 cords in moderate climates and 5-8 cords in cold climates. Maine, Minnesota, North Dakota and Alberta homeowners often go through 6-10 cords. Supplemental wood heat (evenings and weekends) uses 1-2 cords.
Appliance efficiency drives the numbers. An open masonry fireplace loses 80-90% of the heat up the chimney. An EPA-certified wood stove captures 60-80%. A high-efficiency pellet stove or outdoor wood boiler reaches 80-90%. The same 25M BTU cord delivers 2-5M usable BTU through an open fireplace versus 18-22M through a modern stove.
Firewood safety and mistakes
Three mistakes account for most firewood-related house fires. Burning unseasoned wood deposits creosote in the chimney at three to four times the normal rate; the creosote then ignites, causing a chimney fire. Skipping the annual chimney sweep is the second - National Fire Protection Association NFPA 211 requires one inspection per year, with sweeping as needed.
Pressure-treated lumber, painted wood, plywood, MDF, and railroad ties release toxic gases (arsenic, formaldehyde, creosote) when burned. The EPA's Burn Wise program lists these as never-burn materials. Even outdoor fire pits should stick to natural cordwood. Burning treated wood indoors is a serious health hazard.
The third common mistake is buying a "cord" that turns out to be a face cord, then complaining mid-winter that the wood ran out. Knowing your stack volume up front - which is what this calculator is for - removes the ambiguity. A few minutes with a tape measure prevents a costly January phone call.