Firewood Cord Chart: Cords, Face Cords & BTUs by Species

How much wood is in a face cord?

On the defaults — a stack 8 feet long, 4 feet high, of 16-inch red oak — the stack is 42.67 cubic feet, 0.33 cords, 1.00 face cords and 8.20 million BTU, and at $250.00 a cord it costs $83.33. A full cord is 128 cubic feet of stacked wood — a stack 4 feet high, 8 feet long and 4 feet deep. A face cord is one-third of a cord: a 4-by-8-foot stack of 16-inch pieces, 42.67 cubic feet. The heat in a cord is measured in millions of BTU and depends on the species: dense hardwoods like hickory and oak hold roughly twice the heat of softwoods like pine.

Five things about the model are worth stating plainly. First, the cubic feet are the length times the height times the piece length in feet — 8 × 4 × (16 ÷ 12) = 42.67. Second, the cords are the cubic feet divided by 128 — 42.67 ÷ 128 = 0.33. Third, the face cords are the cubic feet divided by 42.67 (128 ÷ 3) — 42.67 ÷ 42.67 = 1.00. Fourth, the heat is the cords times the species BTU per cord — 0.33 × 24.6 = 8.20 million BTU. And fifth, the cost is the cords times the price per cord — 0.33 × $250.00 = $83.33; all listed in Accuracy & limitations.

The species chart — heat per cord, seasoned wood

The face-cord BTU is the cord BTU divided by 3. Shagbark hickory is the hottest wood in the chart at 27.7 million BTU a cord; white pine is the coolest at 15.9. A cord of hickory holds about 74% more heat than a cord of white pine — so the species matters more than the stack size when you are buying heat.

The worked example, line by line

Setup: stack 8 feet long, 4 feet high, 16-inch pieces, red oak, $250.00 a cord.

Line 1 — the cubic feet. The cubic feet are 8 × 4 × (16 ÷ 12) = 42.67.

Line 2 — the cords. The cords are 42.67 ÷ 128 = 0.33.

Line 3 — the face cords. The face cords are 42.67 ÷ 42.67 = 1.00 — one face cord is one-third of a full cord.

Line 4 — the heat. The heat is 0.33 × 24.6 = 8.20 million BTU.

Line 5 — the cost. The cost is 0.33 × $250.00 = $83.33.

Line 6 — the check. Three face cords make a full cord: 3 × 42.67 = 128.00 cubic feet, 3 × 8.20 = 24.60 million BTU, 3 × $83.33 = $250.00.

Every branch, checked

Full cord of red oak (8 ft × 4 ft × 48 in): 128.00 cubic feet; 1.00 cords; 3.00 face cords; 24.60 million BTU; $250.00 — A full cord is a stack 4 feet high, 8 feet long and 4 feet deep — 128.00 cubic feet of stacked wood, 24.60 million BTU of red oak, and $250.00 at $250.00 a cord. It is three face cords, three times the heat, three times the price.

White oak face cord: 42.67 cubic feet; 0.33 cords; 1.00 face cords; 8.80 million BTU; $83.33 — White oak holds a little more heat than red oak — 26.4 million BTU a cord against 24.6 — so a face cord gives 8.80 million BTU instead of 8.20, for the same $83.33.

Two face cords of red oak (16 ft × 4 ft × 16 in): 85.33 cubic feet; 0.67 cords; 2.00 face cords; 16.40 million BTU; $166.67 — Doubling the stack length to 16 feet doubles everything: 85.33 cubic feet, 0.67 cords, 2.00 face cords, 16.40 million BTU and $166.67.

Hickory face cord: 42.67 cubic feet; 0.33 cords; 1.00 face cords; 9.23 million BTU; $83.33 — Shagbark hickory is the hottest wood in the chart — 27.7 million BTU a cord — so a face cord gives 9.23 million BTU, the most heat for the same $83.33.

White pine face cord: 42.67 cubic feet; 0.33 cords; 1.00 face cords; 5.30 million BTU; $83.33 — White pine is the coolest wood in the chart — 15.9 million BTU a cord — so a face cord gives only 5.30 million BTU for the same $83.33. Pine is cheap heat per dollar, but you burn nearly twice as much of it.

Full cord at $300.00/cord: 128.00 cubic feet; 1.00 cords; 3.00 face cords; 24.60 million BTU; $300.00 — At $300.00 a cord the same full cord of red oak costs $300.00 — the heat is unchanged at 24.60 million BTU, only the price moves.

12-ft stack of red oak: 64.00 cubic feet; 0.50 cords; 1.50 face cords; 12.30 million BTU; $125.00 — A 12-foot stack is half a cord: 64.00 cubic feet, 1.50 face cords, 12.30 million BTU and $125.00.

The reverses, worked backwards

Smallest whole-foot stack length for 1 full cord: At the displayed 24 ft the figures are 128.00 cubic feet; 1.00 cords; 3.00 face cords; 24.60 million BTU; $250.00. At the displayed 24 ft the stack is a full cord: 128.00 cubic feet, 1.00 cords. At 23 ft the stack is 122.67 cubic feet, 0.96 cords and 2.88 face cords — below a full cord — so 24 ft is the smallest whole-foot length for 1 full cord.

Smallest whole-foot stack length for 2 face cords: At the displayed 16 ft the figures are 85.33 cubic feet; 0.67 cords; 2.00 face cords; 16.40 million BTU; $166.67. At the displayed 16 ft the stack is 2.00 face cords. At 15 ft the stack is 80.00 cubic feet, 0.63 cords and 1.88 face cords — below 2 face cords — so 16 ft is the smallest whole-foot length for 2 face cords.

Smallest whole-foot stack length for 10 million BTU of red oak: At the displayed 10 ft the figures are 53.33 cubic feet; 0.42 cords; 1.25 face cords; 10.25 million BTU; $104.17. At the displayed 10 ft the stack gives 10.25 million BTU. At 9 ft the stack gives 9.23 million BTU — below 10 — so 10 ft is the smallest whole-foot length for 10 million BTU of red oak.

Smallest whole-foot stack length for a $500.00 cost at $250.00/cord: At the displayed 48 ft the figures are 256.00 cubic feet; 2.00 cords; 6.00 face cords; 49.20 million BTU; $500.00. At the displayed 48 ft the cost is $500.00. At 47 ft the cost is $489.58 — below $500 — so 48 ft is the smallest whole-foot length for a $500.00 cost at $250.00 a cord.

Largest whole-foot stack length for the cost to STAY at or below $100.00 at $250.00/cord: At the displayed 9 ft the figures are 48.00 cubic feet; 0.38 cords; 1.13 face cords; 9.23 million BTU; $93.75. At the displayed 9 ft the cost is $93.75. At 10 ft the cost is $104.17 — above $100 — so 9 ft is the largest whole-foot length for the cost to stay at or below $100.00.

Smallest whole-foot stack length for 20 million BTU of hickory: At the displayed 18 ft the figures are 96.00 cubic feet; 0.75 cords; 2.25 face cords; 20.78 million BTU; $187.50. At the displayed 18 ft the stack gives 20.78 million BTU of hickory. At 17 ft the stack gives 19.62 million BTU — below 20 — so 18 ft is the smallest whole-foot length for 20 million BTU of hickory.

What the defaults assume

The defaults are a stack 8 feet long, 4 feet high, of 16-inch red oak, at $250.00 a cord — 42.67 cubic feet; 0.33 cords; 1.00 face cords; 8.20 million BTU; $83.33. With Full cord of red oak (8 ft × 4 ft × 48 in), 128.00 cubic feet; 1.00 cords; 3.00 face cords; 24.60 million BTU; $250.00. With White oak face cord, 42.67 cubic feet; 0.33 cords; 1.00 face cords; 8.80 million BTU; $83.33. With Two face cords of red oak (16 ft × 4 ft × 16 in), 85.33 cubic feet; 0.67 cords; 2.00 face cords; 16.40 million BTU; $166.67. With Hickory face cord, 42.67 cubic feet; 0.33 cords; 1.00 face cords; 9.23 million BTU; $83.33. With White pine face cord, 42.67 cubic feet; 0.33 cords; 1.00 face cords; 5.30 million BTU; $83.33. With Full cord at $300.00/cord, 128.00 cubic feet; 1.00 cords; 3.00 face cords; 24.60 million BTU; $300.00. With 12-ft stack of red oak, 64.00 cubic feet; 0.50 cords; 1.50 face cords; 12.30 million BTU; $125.00. With 0-ft stack, 0.00 cubic feet; 0.00 cords; 0.00 face cords; 0.00 million BTU; $0.00. With 1-ft stack, 5.33 cubic feet; 0.04 cords; 0.13 face cords; 1.03 million BTU; $10.42. With 100-ft stack, 533.33 cubic feet; 4.17 cords; 12.50 face cords; 102.50 million BTU; $1,041.67. With 12-inch pieces (8 ft × 4 ft), 32.00 cubic feet; 0.25 cords; 0.75 face cords; 6.15 million BTU; $62.50. With Aspen full cord, 128.00 cubic feet; 1.00 cords; 3.00 face cords; 16.80 million BTU; $250.00. With Price $0/cord, 42.67 cubic feet; 0.33 cords; 1.00 face cords; 8.20 million BTU; $0.00 — the wood still measures 0.33 cords and 8.20 million BTU, only the price is zero. With Price $400.00/cord (face cord of red oak), 42.67 cubic feet; 0.33 cords; 1.00 face cords; 8.20 million BTU; $133.33.

Output · formula · meaning

Who uses this

• The homeowner buying a face cord of red oak: they learn it is 42.67 cubic feet, 0.33 cords and 8.20 million BTU for $83.33 — and they check the 24 ft reverse to see the stack length that makes a full cord.
• The buyer comparing hickory and pine: they learn a face cord of hickory gives 9.23 million BTU and a face cord of white pine gives 5.30 — and they check the species chart to see the full 12-species ranking.
• The homeowner with $100.00 to spend: they learn 9 feet of stack costs $93.75 and 10 feet costs $104.17 — and they check the 9 ft reverse to see the longest stack that stays under $100.00.
• The buyer who needs 10 million BTU: they learn a 10-foot stack of red oak gives 10.25 million BTU — and they check the 18 ft reverse to see the hickory stack that gives 20 million BTU.

Accuracy & limitations

The math is first-principles: the cubic feet are the stack length times the stack height times the piece length divided by 12, rounded to two decimals half-up; the cords are the cubic feet divided by 128; the face cords are the cubic feet divided by 128/3 (42.67); the heat is the cords times the species BTU per cord; the cost is the cords times the price per cord. The face-cord divisor is the exact 128/3, not a rounded 42.67 — a rounded divisor would shave the face cords at the second decimal. What the model cannot do is measure your stack: a cord is 128 cubic feet of STACKED wood, and loose or poorly stacked wood holds far less; the BTU figures are for seasoned wood dried 6–12 months to about 20% moisture, and green wood gives far less heat and more smoke; the same species varies with growing conditions and how dry it is; and the figures follow the published firewood tables (USDA Forest Service Wood Handbook / university extension tables), which are approximate by design. Use it to compare species and price a stack — then measure the stack yourself before you pay.

Frequently asked questions