Firewood Cord Calculator
A full cord of firewood is legally defined in the United States as 128 cubic feet of stacked wood. When buying or selling firewood, knowing how many cords are in a pile helps you verify that you are getting what you paid for. This calculator converts the actual dimensions of a firewood stack (height, length, and width or log length) into stacked cubic feet, then divides by 128 to give the number of full cords. It also shows the fraction of a cord and the equivalent face cords.
Firewood cord formula
Stacked volume = height × length × log length (ft³)
Full cords = stacked volume / 128
Face cords = full cords × (4 / log length)
One full cord = 4 ft x 4 ft x 8 ft = 128 cubic feet. The face cord conversion uses 4 feet as the standard depth of a full cord. A face cord is always 4 ft high by 8 ft long but only one log-length deep, so its volume equals 128 * (log length / 4) cubic feet.
Firewood buying tips
- Always ask for the price per full cord (128 cubic feet stacked), and insist the seller defines the log length so you can verify the volume.
- Seasoned firewood (dried for 6 to 12 months) produces significantly more usable heat than green wood, which loses energy evaporating moisture.
- Stack firewood loosely with air circulation to continue drying; cover the top but leave the sides open.
- High-density hardwoods such as oak, hickory, and ash provide more BTUs per cord than softwoods or low-density hardwoods.
- Many US states require sellers to provide a receipt showing the number of full cords sold. Check your state consumer protection office for firewood sale regulations.
Firewood cord calculator: frequently asked questions
What is a full cord of firewood?
A full cord of firewood is a stack measuring 4 feet high by 4 feet wide by 8 feet long, totaling 128 cubic feet of stacked wood, air, and bark. It is the standard legal unit of measure for firewood in the United States. Most states have laws defining a cord and regulating firewood sales.
What is a face cord or rick?
A face cord (also called a rick) is a stack 4 feet high by 8 feet long, but only as deep as the length of the individual pieces. Common log lengths of 16 inches produce a face cord of about 42 to 43 cubic feet, roughly one-third of a full cord. This calculator uses the actual dimensions you enter.
Why is there a difference between stacked volume and solid wood volume?
A cord of stacked firewood is about 80 cubic feet of solid wood and 48 cubic feet of air space between the logs. The 128 cubic feet figure includes all the air gaps. Solid wood volume is typically 60 to 65 percent of stacked volume, depending on log shape and how tightly the wood is stacked.
How much firewood do I need for a heating season?
A well-insulated home of 1,500 to 2,000 square feet in a cold climate (such as the northern United States) typically uses 3 to 6 full cords per heating season when wood is the primary heat source. Milder climates or better-insulated homes may need 1 to 3 cords. Your actual usage depends on your climate, stove efficiency, and heating habits.
Does wood species affect heat output per cord?
Yes. Denser hardwoods produce more BTUs per cord than lighter softwoods or low-density hardwoods. An oak or hickory cord contains roughly twice the usable heat energy of the same volume of pine or poplar. The USDA Forest Service publishes heat content data (BTU per cord) by species.
Official sources
- USDA Forest Service: Forest Products - Biomass and Wood Energy.
- NIST Handbook 130 (2024) - Uniform Laws and Regulations (definition of cord): NIST Handbook 130.
Reviewed by the CalculatorHub team, edited by James Graham, 15 June 2026. See our methodology.