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Woodworking Math

Firewood cord calculator

Measure a woodpile's length and height and the length of its pieces. You get the cords it holds, the face cords at that piece length, its volume in cubic feet and cubic meters, what your truck bed holds stacked, and what a cord of your species weighs at the moisture you give it.

Measure at a few places along the pile and use the average.
How long the split pieces are: the depth of one row.
Rows of pieces back to back. Three rows of 16 in make a 4 ft deep stack.
Truck bed: what it holds stacked
Between the wheel wells if you stack below them.
Usually the top of the bed sides.

Wood thrown loosely into a bed takes more room than a stack: the Maine Forest Service counts a cord of 12–16 in pieces as 180 ft³ thrown. That is one source, so this calculator works stacked wood only.

Median of 3 sources

Cords

1 cord

128 ft³ (3.62 m³)

One source: NIST, publisher of Handbook 130, the method-of-sale regulation the states adopt

3 face cords of 16 in pieces

A face cord of 16 in pieces is 0.333 of a cord.

Traditional rule, stated by University of Wisconsin-Extension, Maine Forest Service, University of Arkansas Cooperative Extension and Illinois Extension

Handbook 130 (§2.4.4) bars "face cord", "rack", "pile" and "truckload" in a firewood sale: where your state adopts it, wood is sold by the cord, its fractions or the cubic meter.

Why: A cord is 128 ft³ of stacked wood (NIST Handbook 130), so 8 × 4 ft × 4 ft deep = 128 ft³ is 1 cord.

Why these numbers?

  1. The situation

    A stack 8 ft long and 4 ft high, 3 rows of 16 in pieces (4 ft deep).

    From your input: the stack and the piece length

  2. What that means

    A cord is the wood in 128 ft³ when it is ranked and well stowed: pieces in a row, touching and parallel, stacked compactly (HB 130-2026, Method of Sale §2.4.1.2).

    One source: NIST, publisher of Handbook 130, the method-of-sale regulation the states adopt , sources [1]

  3. So

    8 × 4 × 4 = 128 ft³; ÷ 128 = 1 cord.

    Arithmetic: exact by definition

  4. What that means

    A face cord is a stack 4 ft high and 8 ft long, as deep as the pieces are long: here 4 × 8 × 16/12 = 42.67 ft³, 0.333 of a cord.

    Traditional rule: University of Wisconsin-Extension, Maine Forest Service, University of Arkansas Cooperative Extension and Illinois Extension , sources [2, 3, 4, 5]

  5. The number

    Handbook 130 (§2.4.4) bars "face cord", "rack", "pile" and "truckload" in a firewood sale: where your state adopts it, wood is sold by the cord, its fractions or the cubic meter.

    One source: NIST, publisher of Handbook 130, the method-of-sale regulation the states adopt , sources [1]

How we source these numbers

How a cord of wood is measured

A cord is the wood in 128 cubic feet of space when it is ranked and well stowed: pieces laid in rows, touching and parallel, stacked compactly. That is the definition in NIST Handbook 130, the method-of-sale regulation most states adopt, and it is why a cord is usually pictured as a pile 4 feet high, 4 feet deep and 8 feet long. Multiply length by height by depth in feet and divide by 128 for cords.

A face cord, also called a rick or stove cord, is a single row 4 feet high and 8 feet long, as deep as the pieces are long. With 16 inch pieces it is a third of a cord; with 24 inch pieces, half. Because the depth changes, a face cord price means nothing until you know the piece length, which is why Handbook 130 bars the term, along with "truckload", in a firewood sale. Divide the price by the fraction of a cord to compare sellers.

A cord holds about 85 cubic feet of solid wood; the rest is air, and the sources put it between 79 and 90. The weight multiplies that by the species' density at your moisture content from the USDA Wood Handbook, the same equations as the wood weight calculator. Fresh-cut wood can be half water by weight; firewood burns well at 20% moisture or less, which a moisture meter on a freshly split face will tell you.

For a truck, measure the inside of the bed and the height you will stack to; the helper treats it as a stacked box. Wood thrown in loosely takes more room, so a thrown load is less wood than the same bed stacked. The same site has a fence calculator and a stair calculator.

Sources

  1. NIST, Handbook 130-2026, Uniform Regulation for the Method of Sale of Commodities, §2.4 Fireplace and Stove Wood (2.4.1.2 Cord; 2.4.4 Prohibition of Terms), read 2026-11-07
  2. University of Wisconsin-Extension, A. J. Martin, What Is A Cord? (Forestry Facts No. 44, 1989), read 2026-11-07
  3. Maine Forest Service, Firewood facts: how is wood measured and sold? (2017), read 2026-11-07
  4. University of Arkansas Cooperative Extension, S. Sadaka and J. W. Magugu, Basics of Heating with Firewood (FSA1091), read 2026-11-07
  5. Illinois Extension, R. Hentschel, How to measure and handle firewood (Over the Garden Fence, 27 Dec 2020), read 2026-11-07
  6. Illinois Extension, Firewood: buying and selling, read 2026-11-07
  7. US EPA, Burn Wise: best wood-burning practices, read 2026-11-07
  8. NIST, Special Publication 811, Appendix B (1 ft = 0.3048 m, 1 in = 25.4 mm)

How we source these numbers