Firewood Math

Firewood Cord Calculator

By Tam Vu · Updated

On this page
  1. How the calculator works
  2. Example
  3. Measuring tips

Measure the stack, enter the numbers, and see what you actually have. Works for a stack in your yard or a load a seller just delivered.

Stack size

Assumes a tight, evenly stacked pile. Loosely thrown wood has more air and less wood than its outside size suggests.

How the calculator works

A full cord is a tightly stacked pile of wood and air space that measures 128 cubic feet — usually 4 feet high, 8 feet long and 4 feet deep. So:

  • Cubic feet = length × height × (piece length in inches ÷ 12)
  • Full cords = cubic feet ÷ 128
  • Face cords = (length × height) ÷ 32, because a face cord is one 4 ft × 8 ft face of wood at whatever piece length the seller cuts
A full cord is 8 ft long, 4 ft high and 4 ft deep (128 cubic feet). A face cord of 16-inch pieces has the same face but is only 16 inches deep, about one third of a cord.
Same front, different depth: three face cords of 16-inch wood make one full cord.

The piece length is the depth of the stack. With 16-inch pieces, one face cord is a third of a full cord. With 12-inch pieces it is only a quarter.

Example

A seller delivers a stack 10 ft long and 4 ft high, with 16-inch pieces, for $180.

  • 10 × 4 × (16 ÷ 12) = 53.3 cubic feet
  • 53.3 ÷ 128 = 0.42 full cords
  • Price per full cord equivalent: $180 ÷ 0.42 = about $432

That's how you compare a "face cord for $180" against "a full cord for $400" — convert both to price per full cord.

Measuring tips

  • Measure the average height. Stacks settle and lean; take the height at several points.
  • Measure piece length on several pieces — sellers' "16-inch" wood is often shorter.
  • Only count the wood that is actually stacked tight. Big gaps, crooked pieces and loose tops mean less wood.
  • Thrown or dumped wood in a truck bed can't be measured accurately. Stack it, then measure.