1 cord = 128 cubic feet I don’t care how it’s stacked. I always considered a face cord 1/3 of a cord. Here’s some info from
https://forestry.usu.edu/forest-products/wood-heating I find the face cord description interesting.
Firewood Volume
Though firewood dry weight is important for determining heat content, firewood is normally bought and sold by volume. The most common unit of firewood volume is the cord, also known as a standard or full cord. A cord is an evenly-stacked pile containing 128 cubic feet of wood and air space. Though a cord can be piled in any shape, a standard cord is generally thought of as a stack of wood 4 feet tall, 8 feet long, and 4 feet deep (Figure 1). To figure the number of cords in another size or shape pile, determine the pile's cubic foot volume and divide by 128. A randomly-piled stack of wood will generally contain more air and less wood than one neatly piled.
Some dealers sell wood by the face cord or short cord (Figure 2). A face cord is a stack of wood 4 feet high, 8 feet long, and as deep as the pieces are long. Pieces are commonly 12 to 18 inches long, so a face cord may contain 32 to 48 cubic feet of wood and air.
Another common firewood measure is the pickup load (Figure 3). This is a very imprecise but common measure. A full-size pickup with a standard bed can hold about 1/2 of a full cord or 64 cubic feet when loaded even with the top of the bed. Small pickups hold much less. Random loading will decrease this amount further.
A randomly-piled stack or pickup load of wood will contain more air and less wood than one neatly stacked. Crooked, small diameter, and knotty or branchy pieces also reduce the amount of wood in a pile.
Figure 1. Standard Cord
Total Volume = 128 cubic feet
Figure 2. Face Cord
Total Volume = 32 to 48 cubic feet (depending on piece length)
Figure 3. Pickup Load
Approximate Total Volume = 64 cu. ft.
Buying Firewood
Species, volume, dryness, and need for splitting should be considered when buying firewood. The information here and in other publications should give you the basic information you will need to be an informed buyer. However, knowing your dealer is the best way to ensure that you are getting what you are paying for.