Firewood cord calculator

How big is a cord of wood?

NIST Handbook 130 defines a cord as the wood in 128 cubic feet when it is ranked and well stowed — pieces parallel, touching and stacked compactly. The classic stack is 4 ft high, 4 ft deep and 8 ft long.

What is a face cord?

A stack 4 ft high and 8 ft long but only one log deep. With 16-inch logs that is 4 × 8 × 1.33 = 42.7 cubic feet — one-third of a cord.

Can sellers use “face cord” or “rick”?

Not under the NIST model law: it says firewood should be sold by the cord or fractions of a cord (or cubic meters), and that terms such as “face cord” and “rack” shall not be used. Each state decides whether it adopts these rules.

How do I measure my pile?

Measure the length and height of the stack and the length of the pieces (the depth). Multiply them in feet and divide by 128.

What about loose, thrown wood?

Thrown wood takes up more space than a stacked cord, so the same volume of loose wood holds less wood. The calculator assumes a tight stack.

How many face cords make a full cord?

It depends on the length of the logs. Where the term is used, a face cord is 4 ft high and 8 ft long and one log deep, so its volume is 32 square feet of face times the log length. With 16-inch logs it is 42.7 cubic feet, 0.333 of a cord, so three make a cord; with 12-inch logs it is 0.250 of a cord, so four make a cord; with 24-inch logs, half a cord.

How can I check that I got a full cord?

Stack the wood neatly and measure it: length × height × depth in feet should come to at least 128 cubic feet, the volume of a cord. A stack 4 ft high, 4 ft deep and 8 ft long is 1.00 cord. Count the stack only when it is tightly piled, and measure after the wood has settled, since loose or thrown wood leaves gaps.

The formula

Cords = length × height × depth in feet ÷ 128. NIST Handbook 130 defines a cord as 128 cubic feet of wood that is ranked and well stowed, which is the 4 by 4 by 8 ft stack. The depth is the length of the logs when the stack is one row deep. The calculation measures the space the stack fills, including the gaps between logs, which is why the legal definition requires the pieces to be parallel, touching and compactly stacked.

Worked example: a stack of 16-inch logs

A stack 12 ft long and 5 ft high of 16-inch logs fills 12 × 5 × 1.333 = 80.0 cubic feet, which is 0.625 cord (1.87 face cords of 16-inch logs). The same stack of 24-inch logs, two feet deep, would be 0.938 cord. A full 4 by 4 by 8 stack is exactly 1 cord.

Common mistakes

Measuring the stack height at the lowest point of a sagging or sloping stack gives too much, and so does counting the space between rows. Mixing log lengths in one stack without measuring the depth of each is another. A third is comparing prices for “a cord” and “a rick” or “face cord” without checking the dimensions, as the model rules ask sellers to sell firewood by the cord or a fraction of it rather than by those terms. The calculator gives a volume of stacked wood, not the heat content: seasoned wood and species with higher density give more heat for the same volume.

Sources: NIST Handbook 130, Uniform Laws and Regulations (Uniform Regulation for the Method of Sale of Commodities: firewood sold by the cord of 128 cubic feet, ranked and well stowed). Related: cubic feet calculator, cubic yard calculator, lumber calculator and propane calculator.