Measure your stacked firewood in cords
Measure a compact rectangular stack in feet. Enter its length along the row, its average height and its depth from front to back. For stacks of different sizes, work out each stack separately and add the results.
Example: 8 × 4 × 2 feet makes 64 cubic feet, or half a cord.
Multiply the three measurements for stacked cubic feet, then divide by 128. A loose heap in a truck bed needs to be stacked before this comparison is meaningful.
Translate the quantity into a usable measure
Florida's Department of Agriculture and Consumer Services explains a cord as 128 cubic feet of compactly stacked wood. Its example is a stack four feet by four feet by eight feet. For a bulk purchase quoted as a fraction of a cord, ask the seller to state that fraction rather than just a description of the vehicle.
Compare like quantities before comparing price
Half a cord is 64 stacked cubic feet. A stack four feet high, four feet deep and four feet long has that volume. A pile with the same outside dimensions can contain very different air spaces. Agree how the quantity is described, whether stacking is included and where the delivery can be placed.
Ask two other questions about the wood
The cord is a measure of volume. It does not establish whether the pieces fit the firebox or how much moisture they contain. Ask about split length and the condition of the wood separately. Leave an access path and store fuel away from the fireplace and other heat sources.