What Is the Cost per BTU of Firewood (BTU Chart & Costs)

The cost of firewood per useful unit of heat depends on more than the price per cord. Compare each wood’s heat content, moisture level, and your stove’s efficiency. For example, at the sample prices below, birch costs about $18.39 per useful million BTU, while oak costs about $20.71. Your local prices and actual wood condition can change the result.

A firewood price tag is a bit like a grocery price: the cheapest package is not always the best value if it contains less of what you need. With firewood, the useful measure is the heat you get for your money, not just the cost of a cord. I use the calculation below to make that comparison clearer.

Firewood BTU by Species: What a Cord Really Delivers

A BTU is a unit of heat. A cord of wood does not have one fixed heat value: species, density, piece size, and moisture all affect how much heat it holds. The ranges below are approximate for seasoned wood at roughly 20% moisture content or less, not a promise for every load.

MMBtu means one million British thermal units. These figures describe the wood’s approximate heat content, not the heat that will warm your home. Some heat leaves through the chimney, so your appliance’s efficiency matters too.

A standard cord is a stack measuring 4 feet high, 4 feet wide, and 8 feet long, or 128 cubic feet of stacked wood. The spaces between pieces are part of that measurement. Piece size and how neatly the wood is stacked affect the amount of solid wood in a stack, so confirm that a seller’s stated volume matches what you are buying.

The ranges overlap. Birch may have more heat per cord than some oak, while a particular dry oak load may outperform a wetter birch load. Use species as a starting point, then factor in moisture and price.

Cost per Useful BTU: Moisture, Appliance Efficiency, and Price

Cost per useful MMBtu estimates what you pay for heat that reaches your room, rather than heat contained in the wood. To calculate it, divide the delivered price per cord by the heat per cord multiplied by your appliance’s efficiency. Use the same units for every wood type so the comparison stays fair.

Formula: price per cord ÷ (MMBtu per cord × appliance efficiency) = cost per useful MMBtu

Use efficiency as a decimal: 65% becomes 0.65. If you want a comparison that excludes appliance efficiency, divide the price per cord by the wood’s MMBtu per cord. That gives cost per MMBtu in the wood, not cost per useful MMBtu.

These prices are examples, not local market quotes. For instance, oak costs $350 ÷ (26 × 0.65), or about $20.71 per useful MMBtu. Birch’s sample result is lower, even though both are assigned 23 MMBtu per cord, because birch has the lower example price.

The chart assumes the same 65% appliance efficiency for every wood. If your appliance has a different rated efficiency, use that figure instead. Check its manual or product information; do not treat the example efficiency as a rating for your stove.

Why moisture changes the comparison

Moisture content is the water in the wood, expressed as a share of its weight. Wet wood has less usable heat for a given amount of wood because heat is spent driving off water. It can also increase creosote, a flammable deposit that may build up in a chimney or flue.

The chart’s heat estimates apply to seasoned wood at roughly 20% moisture or less. A seller’s species claim alone does not confirm that condition. If you can, check the wood’s moisture with a suitable meter and follow the meter’s instructions. Make sure the reading reflects the split face of a piece, rather than only its outer surface.

Compare Delivered Firewood Prices Before You Buy

A useful price comparison includes the delivered cost, amount of wood, species, and moisture condition. A low advertised price may not be a bargain if the load is smaller than a cord, wetter than expected, or a different mix of species. Ask for clear details before comparing the cost per useful MMBtu.

For each seller, record:

• Delivered price, including any fees
• Stated volume and how it is measured
• Wood species or species mix
• Whether the wood is seasoned, and its measured moisture if available
• Your appliance’s efficiency, if known

Then estimate the heat per cord using the species chart, and apply the formula. For mixed loads, you need the amount and estimated heat for each species to make a meaningful estimate. If the mix or volume is unclear, the result will be less reliable.

Here are two sample buying scenarios using the chart’s assumptions:

These are worked examples, not reports of actual purchases. They show why comparing cord prices alone can mislead: the oak costs more per cord and also has more estimated heat, but the birch still costs less per unit of useful heat at these sample prices.

At the same price and efficiency, wood with more heat per cord generally costs less per unit of heat. But a higher price can cancel out that advantage. Use local delivered prices and the condition of the wood to decide.

Cutting and Processing Firewood Safely

Cutting your own wood adds equipment, fuel, and safety to the cost calculation. A chainsaw is a powerful tool, and its bar, chain, fuel mix, and operating settings must match the saw maker’s instructions. Do not guess at a chain size or assume one fuel ratio works for every saw.

Before cutting, wear appropriate chainsaw protective gear and check the site. Look for overhead hazards, stable footing, a clear escape route, nearby people, and the tree’s lean. Follow applicable OSHA logging requirements and ANSI Z133 guidance where they apply.

Prepare the saw according to its operator’s manual. Inspect the saw, chain brake, bar, chain tension, and lubrication. Use only the bar and chain specification, fuel mix, and operating settings listed for that model. If anything is unclear, stop and check the manual rather than testing an assumed setup.

Cut on stable supports and use sound bucking technique. Keep bystanders clear. A hung-up, leaning, or tensioned stem can split suddenly in a dangerous failure called a barber-chair. This can cause fatal injury. Do not try to cut a stem beyond your training or control; get a qualified professional if it is hung up, under significant tension, or difficult to manage.

Seasoning, Storage, and Saw Care

Seasoning means drying split wood before burning it. The target for this guide’s heat estimates is about 20% moisture or less. Stack wood to allow airflow, and check its condition rather than relying only on how long it has been stored. Dryness affects the heat you can use and helps avoid the added risks of burning wet wood.

After cutting, stop the saw and let it cool. Clean and inspect it as directed in the manual, and store fuel safely according to the product instructions and local rules. These steps do not change the wood’s BTU value, but they matter if you are including the cost and effort of processing your own supply.

Keep a simple record of species, moisture, delivered volume, price, and appliance efficiency. With those details, you can compare your next load using the same calculation instead of relying on a cord price alone.

Quick Answers About Firewood Cost per BTU

These answers address the common questions behind a firewood cost comparison. The key is to distinguish heat in the wood from heat your appliance can use. Check your load’s price, volume, and moisture, then use the formula above to estimate cost per useful MMBtu for a consistent comparison.

What is the cost per BTU of firewood?
It varies by wood, moisture, price, and appliance efficiency. The sample values range from $18.39 to $20.71 per useful MMBtu.

How do I calculate firewood cost per useful MMBtu?
Divide the delivered price per cord by the wood’s MMBtu per cord multiplied by appliance efficiency as a decimal.

How many BTUs are in a cord of oak?
The approximate range for seasoned oak is 24–29 million BTU per cord. The exact amount varies with species, density, and moisture.

Which firewood gives the most heat per cord?
There is no single fixed result for every load. In the estimates here, oak reaches about 29 million BTU per cord, but the listed species ranges overlap.

Is a cheaper cord always the better deal?
No. Compare the delivered price with estimated heat, moisture, and appliance efficiency. A lower cord price may still mean a higher cost per useful MMBtu.

Does wet firewood have the same heat value as seasoned wood?
No. Wet wood delivers less usable heat because energy is used to drive off water. The chart applies to wood at roughly 20% moisture or less.

How big is a standard cord of firewood?
A standard cord is 128 cubic feet of stacked wood, commonly arranged in a stack 4 feet by 4 feet by 8 feet.

Should I include stove efficiency in the calculation?
Yes, if you want to estimate useful heat. If you only want to compare heat content in the wood, divide the cord price by MMBtu per cord and leave efficiency out.

(This article was written by one of our staff writers, Evan Bradley. Visit our Meet the Team page.)