Firewood Volume Metrology: Full Cords, Quarter Cords, and Solid Wood Yield
Purchasing, stacking, seasoning, and transporting fuelwood requires an exact understanding of volumetric trade standards. Across the forestry and residential heating sectors, the primary unit of commercial firewood measurement is the standard cord. However, consumers, arborists, and firewood vendors frequently trade in smaller increments, most notably the quarter cord, half cord, and the often misunderstood face cord (or “rick”). Converting accurately between full cords and quarter cords—and understanding the physical air-to-wood ratio within a stacked pile—is essential to prevent consumer fraud and ensure accurate heating capacity calculations.
Quick Summary: Firewood Volume and Stack Geometry
Under international weights and measures standards (including NIST Handbook 130), a standard full cord of firewood represents a tightly ranked and well-stowed stack containing exactly 128 cubic feet ($3.62456text{ m}^3$) of wood, bark, and intervening air spaces:
- $mathbf{1text{ Full Cord}} = 4text{ Quarter Cords} = 128text{ ft}^3 approx 3.625text{ m}^3text{ (stacked volume)}$
- $mathbf{1text{ Quarter Cord}} = 0.25text{ Cords} = 32text{ ft}^3 approx 0.906text{ m}^3text{ (stacked volume)}$
- $mathbf{1text{ Half Cord}} = 0.50text{ Cords} = 64text{ ft}^3 approx 1.812text{ m}^3text{ (stacked volume)}$
- Solid Wood Ratio: Due to irregular cylindrical log shapes and bark crevices, a standard 128 cu ft stack contains only 70 to 90 cubic feet (average ~85 cu ft) of actual solid wood fiber.
Stack Dimensions and Physical Configurations
A cord is defined strictly by its external volumetric envelope when wood is neatly stacked parallel:
1. Standard Full Cord ($128text{ ft}^3$)
The archetypal configuration is a stack measuring $4text{ feet high} times 4text{ feet wide} times 8text{ feet long}$ ($4text{ ft} times 4text{ ft} times 8text{ ft} = 128text{ ft}^3$). In practical residential cords, firewood is rarely cut into 4-foot lengths; instead, pieces are cut into 16-inch or 24-inch stove lengths. A full cord of 16-inch firewood therefore consists of three parallel rows, each measuring $4text{ ft high} times 8text{ ft long}$ ($3 times [4text{ ft} times 1.333text{ ft} times 8text{ ft}] = 128text{ ft}^3$).
2. Quarter Cord ($32text{ ft}^3$)
A quarter cord contains exactly one-fourth the gross volume of a full cord: $128 / 4 = 32text{ cubic feet}$. Common stacking dimensions for a quarter cord include:
- A single row of 12-inch long firewood: $4text{ ft high} times 8text{ ft long} times 1text{ ft wide} = 32text{ ft}^3$.
- A single row of 16-inch firewood: $4text{ ft high} times 6text{ ft long} times 1.333text{ ft wide} = 32text{ ft}^3$.
- A cube stack: $4text{ ft high} times 4text{ ft wide} times 2text{ ft deep} = 32text{ ft}^3$.
The “Face Cord” Trap: Why Legal Regulations Prohibit Face Cords
One of the most pervasive consumer pitfalls in firewood purchasing is the informal term “face cord” (also referred to as a “rick” or “tier”). A face cord refers to a single stack measuring 4 feet high and 8 feet long, but with whatever depth the wood was cut to:
- If logs are cut to 16 inches ($1.333text{ ft}$), the face cord volume is $4 times 8 times 1.333 = 42.67text{ ft}^3$, which equals $1/3$ of a full cord.
- If logs are cut to 12 inches ($1.0text{ ft}$), the face cord volume is $4 times 8 times 1.0 = 32.0text{ ft}^3$, which equals exactly $1/4$ of a full cord (a quarter cord).
- If logs are cut to 24 inches ($2.0text{ ft}$), the face cord volume is $4 times 8 times 2.0 = 64.0text{ ft}^3$, which equals $1/2$ of a full cord.
Because the term “face cord” can vary in volume by more than 100% depending solely on cut length, NIST Handbook 130 and most state weights and measures statutes prohibit advertising or selling firewood under terms such as “face cord,” “rick,” “rack,” or “truckload.” Fuelwood must legally be sold by the cord, fractional cord, or by cubic volume.
Firewood Stacking Volume Comparison Table
| Unit Designation |
Stacked Volume (ft³) |
Stacked Volume (m³) |
Est. Solid Wood (ft³) |
Equivalent Full Cords |
16-in Log Rows (4×8 ft) |
| Full Cord |
$128text{ ft}^3$ |
$3.625text{ m}^3$ |
$80 – 90text{ ft}^3$ |
$1.00$ |
$3text{ rows}$ |
| Half Cord |
$64text{ ft}^3$ |
$1.812text{ m}^3$ |
$40 – 45text{ ft}^3$ |
$0.50$ |
$1.5text{ rows}$ |
| Third Cord (16″ Face Cord) |
$42.67text{ ft}^3$ |
$1.208text{ m}^3$ |
$27 – 30text{ ft}^3$ |
$0.333$ |
$1text{ row}$ |
| Quarter Cord |
$32text{ ft}^3$ |
$0.906text{ m}^3$ |
$20 – 22.5text{ ft}^3$ |
$0.25$ |
$0.75text{ rows}$ |
| Eighth Cord (Face Rick 12″) |
$16text{ ft}^3$ |
$0.453text{ m}^3$ |
$10 – 11.2text{ ft}^3$ |
$0.125$ |
$0.375text{ rows}$ |
Thermal Output, Wood Density, and Moisture Content
Physical volume alone does not determine heating performance. Two primary factors dictate heating value ($BTU$ per cord):
- Species Density: Dense hardwoods (e.g., Shagbark Hickory, White Oak, Sugar Maple) contain substantially more wood fiber per cord than softwoods (e.g., White Pine, Aspen, Eastern Hemlock). A seasoned cord of White Oak yields approximately 25.7 million BTUs, whereas a cord of White Pine yields only 14.3 million BTUs.
- Moisture Content: Freshly felled “green” timber contains 50% or more water by weight. Burning unseasoned firewood expends massive thermal energy simply evaporating moisture, reducing net heat output, causing chimney creosote accumulation, and increasing particulate emissions. Proper seasoning reduces moisture below 20%.
Mathematical Conversion Formulas
$$text{Quarter Cords} = text{Full Cords} times 4$$
$$text{Full Cords} = frac{text{Quarter Cords}}{4} = text{Quarter Cords} times 0.25$$
$$text{Stacked Cubic Feet} = text{Full Cords} times 128 = text{Quarter Cords} times 32$$
$$text{Stacked Cubic Meters} = text{Full Cords} times 3.624556 = text{Stacked Cubic Feet} times 0.0283168$$
Cross-Disciplinary Measurement Links
Integrate your firewood calculations with dimensional lumber, volumetric flow, and fastener engineering across our suite:
Authoritative References
