This time of year, it pays to measure your firewood! According to USA Today, thousands of people get ripped off each winter because they don’t know how much a “cord” of wood is. So they wind up paying too much for too little firewood. For those who don’t know, a “cord” is the standard measure of wood in North America. By definition, one cord equals 128 cubic feet. How much is that? Experts say a good visual reference is to imagine a standard sheet of plywood, with four feet of wood stacked on top of it. That’s one cord.

Unfortunately, the Better Business Bureau gets hundreds of complaints each year about dealers who sell wood by the “rack,” the “pallet” or “the truckload.” Experts say you’re taking a huge risk if you buy wood that way, because there are no standardized values attached to those terms. Think about it: A “truckload” will vary depending on the size of the truck. The law offers no protection if you think you’ve overpaid for a stack of wood delivered from a tiny pickup. Know this: You can still get ripped off even when you do buy wood by the cord. That’s the word from Kristin Macey, a spokesperson for the U.S. Division of Measurement Standards. So she offers three simple rules for wood-buyers, to make sure you get exactly what you pay for:

• First: Always measure firewood before you buy it. Grab a tape measure and multiply the width of a stack by its height and length. The total should come out to 128 cubic feet – or 64 cubic feet if you’re only buying half a cord.
• Also: Make sure the wood is stacked correctly. Macey says firewood should be stacked neatly in a row, so that all the pieces are parallel and touching, and with as few gaps as possible.
• Finally know this: Because many new homes have smaller fireplaces, you might buy packaged wood at the supermarket that’s sold by the cubic foot. In the U.S., that’s the only wood that can legally be sold without the word “cord” on the package.