How Long Does a Cord of Firewood Last?

It is October. The cord is stacked against the garage, tarped, looking like plenty. The real question is not whether it will be enough. It is when you will be calling for the second one. That date is knowable, and it is earlier than many first-time buyers guess.

The honest range

Start with the published numbers, because the range is wider than people expect. As a sole heat source with no gas or electric backup, a full cord lasts about five to six weeks. With alternative heating helping, the same cord stretches to ten or twelve weeks, up to three months. Those are the all-day-burning figures. For evening fires only, one or two a week in a standard fireplace, a cord of mixed hardwoods lasts roughly eight to twelve weeks.

Measured in burn hours instead of weeks, a full cord gives about 100 to 120 hours of continuous burning in a conventional fireplace. In a 2,500 square foot house heated around the clock in real cold, that works out to a cord every two to three weeks, though many homeowners burning daily report closer to a cord every five to six weeks once the shoulder seasons are averaged in.

What moves the number

Four levers, in rough order of how much they matter.

The appliance. This is the big one, and the one buyers overlook. A large open fireplace with no air controls can burn through a cord in about seven days of continuous use. A non-catalytic wood stove stretches the same cord to 30 to 60 days. A high-efficiency catalytic stove can make a cord last much of a heating season. Same wood, wildly different mileage. If you are choosing between ambiance and heat, know that the open fireplace is the least efficient way to convert a cord into warmth.

The wood. Dense hardwoods like oak and ash burn longer and hotter than pine or poplar. The BTU chart by species ranks them, but the short version is that a cord of oak and a cord of pine are the same volume and very different amounts of heat. Seasoning matters too: properly seasoned wood burns more efficiently than green wood, so it lasts longer per cord.

The house and the climate. Square footage, insulation, and how cold it gets. A well-insulated house holds heat, so the fire works less. A drafty farmhouse in a northern winter eats wood. This is why national averages are useless and the winter heating guide works by square footage instead.

The fire itself. Roaring fires burn hot and fast; low, steady fires sip. And frequency dominates everything: all-day burning consumes a cord in weeks, while the occasional Friday-night fire stretches it across months. Be honest about which burner you are before you do the math below.

The simple math for your house

A full cord holds roughly 720 pieces of split wood. If you burn 25 logs on a heating day, that is about 29 days per cord. Two fires a week at 8 logs each is 16 logs a week, which stretches the same cord past ten months. The arithmetic is trivial once you count your own fires for a week.

For the whole season, the common rule of thumb is three to six cords per winter for primary heating. Multiply by your local price per cord and you have the seasonal budget. And remember that a cord is 720 decisions about how big a fire to build. Count your fires for a week, do the division, and you will know your date.