Firewood Cords Needed Calculator

Cord vs face cord: the most-confused firewood term

A full cord (also called a “bush cord” or “true cord”) is a precisely defined volume:

4 ft wide × 4 ft tall × 8 ft long = 128 cubic feet of stacked wood

A face cord (also called a “rick” or “running cord”) is the same 4 × 8 ft face but only one log length deep, typically 16 inches:

4 ft × 8 ft × 1.33 ft (16") = 42.7 cubic feet = roughly 1/3 of a full cord

When buying firewood, always clarify which unit. A “$200 cord” might mean a true cord (great deal) or a face cord (overpriced 1/3 cord). Reputable sellers specify; some don’t.

Other related terms:

• Short cord / “Country cord”: 16" logs but volume varies; not standardized
• Stove cord: 16-18" lengths to fit standard stove openings
• Stacked cord: confirmed dimensions when stacked
• Loose cord: thrown into a truck bed; only ~75-80% of stacked volume

Heating value by species (BTU per cord)

Wood species vary dramatically in BTU output. The denser and harder the wood, the more BTU per cord. Air-dried (seasoned) values:

A cord of white oak puts out roughly twice the heat of a cord of white pine. If you’re paying $200/cord for firewood, oak is dramatically cheaper per BTU than pine.

The seasoning requirement

Fresh-cut “green” wood has 30-60% moisture content. It produces:

• Far less heat (water absorbs energy as steam)
• More smoke and creosote
• Difficulty igniting
• Glass on chimney walls
• Risk of chimney fires

Properly seasoned wood is 20% moisture or less (some sources say under 15% for ideal burning). Seasoning timeframes:

Stack technique matters: stacked on pallets above ground, with airflow gaps, covered on top only (not sides), in a sunny location. A neat stack seasons faster than a chaotic pile.

A moisture meter ($20-$40 at any hardware store) tells you when wood is ready. Stab the meter into a freshly-split face: under 20% reads green; 15-20% is ready; under 15% is excellent.

Climate-based heating needs

How much firewood you need depends on climate (heating degree days), home size, insulation, and stove efficiency.

The calculator takes the midpoint of each band above as its baseline, then applies the insulation setting: well-insulated multiplies by 0.8, average by 1.0, and poorly insulated by 1.25.

Then, and this is the step most firewood estimates skip, it divides by the stove efficiency. A cord of oak holds about 24 million BTU, but an 80% stove only puts 19.2 million of that into the house, and an open fireplace closer to 3.6 million.

A 1,800 sq ft well-insulated home in a moderate climate: 1,800 × 40,000 × 0.8 = 57.6 million BTU per season

Burning oak (24M BTU/cord) in an 80% stove, so 19.2M BTU delivered per cord: 57.6 ÷ 19.2 = 3.0 cords per season

The same home in a cold climate (62,500 BTU/sq ft baseline): 1,800 × 62,500 × 0.8 = 90M BTU → 90 ÷ 19.2 = 4.7 cords

Severe climate, poorly insulated: 1,800 × 90,000 × 1.25 = 202.5M BTU → 202.5 ÷ 19.2 = 10.5 cords

Swap that last one to an open fireplace at 15% efficiency and the same house needs 56 cords, which is the arithmetic way of saying an open fireplace cannot heat a house.

Stove efficiency, the biggest variable

Switching from an open fireplace to a modern stove can cut wood usage by 75%. The same heat with a quarter of the wood, and far less smoke, creosote, and indoor air pollution.

Open fireplaces are notoriously inefficient because:

• They pull warm room air up the chimney (often losing more heat than they produce)
• Most heat goes up the flue, not into the room
• They cool the rest of the house during operation
• Indoor air quality suffers

Many fireplaces can be retrofitted with an insert stove (sealed combustion box) that converts them to 70-80% efficiency.

Wood cost vs alternative fuels

For a typical winter heating need (75M BTU effective heat output):

Every row above divides the fuel price by the heat that actually reaches the room, not by the heat in the fuel. That is the only way the comparison means anything, and it is where most published versions of this table go wrong: they charge the fossil fuels their efficiency and quietly give wood and pellets a free pass, which flatters biomass by 20 to 25%.

Self-cut firewood from your own woodlot is by far the cheapest heating fuel, but it represents serious labor (cutting, splitting, hauling, stacking). Most figures price your labor at zero.

Seasoning storage

A 3-cord stack (4×4×24 ft) needs about 100 sq ft of ground. Rules:

• Bottom log should be off the ground (pallets, concrete blocks)
• Stack should have airflow gaps
• Top should be covered (tarp, metal roofing) but sides open
• Avoid stacking against the house (insect bridge, moisture issue)
• South-facing location dries fastest

Most homesteads have a multi-stack rotation:

• Stack A: this winter’s wood (already seasoned)
• Stack B: next winter’s wood (seasoning)
• Stack C: cutting now for 2-3 winters out

Splitting and processing

Wood splits easier when slightly green and easier when frozen. Tools:

• Maul (8 lb): primary tool for hand splitting
• Splitting axe (4-5 lb): better for smaller rounds
• Hydraulic splitter ($1,500-$3,000): essential for large volumes
• Splitting wedge + sledge: backup for tough rounds

A motivated person can split 1/3 cord of pre-cut rounds in a day by hand. With a splitter, a cord per hour is realistic.

Bottom line

A full cord = 128 cubic feet (4×4×8 ft); a face cord is about 1/3 of that. Hardwoods produce 2x the BTU of softwoods. Most homes use 3-5 cords per season; cold climates need more, mild climates less. Modern EPA stoves are 75-85% efficient; open fireplaces are often a net heat loss. Season wood 1-2+ years before burning. Properly stored self-cut wood is the cheapest heating fuel available.