Firewood BTU Calculator

BTU stands for British Thermal Unit — it is the amount of energy needed to raise one pound of water by one degree Fahrenheit. For firewood, BTU per cord tells you how much heat a species can potentially release. Higher BTU wood burns hotter and longer, meaning you burn fewer cords to heat your home through winter.

Osage Orange (Hedge Apple) tops most BTU charts at around 32 million BTU per cord, followed closely by Shagbark Hickory (~27 M BTU) and Black Locust (~26 M BTU). Dense hardwoods consistently outperform softwoods because they pack more combustible material per cord. Oak, Sugar Maple, and Beech are also excellent high-BTU choices that are widely available.

Green or freshly cut wood can lose up to 50% of its effective heat output because energy is wasted evaporating water before combustion begins. Properly seasoned firewood (under 20% moisture content) delivers significantly more usable heat per cord. Most hardwoods need 12–24 months of seasoning split, stacked off the ground, and covered on top to reach ideal moisture levels.

Your stove or fireplace efficiency determines how much of the wood's gross BTU actually heats your home versus escaping up the chimney. An open fireplace may only be 25–30% efficient, while a modern EPA-certified wood stove can reach 75–90% efficiency. Multiplying the gross BTU by your stove's efficiency percentage gives you the effective heat delivered — what this calculator shows as your primary result.

A full cord is a stack of firewood measuring 4 feet wide × 4 feet tall × 8 feet long, totaling 128 cubic feet. In practice, a cord contains roughly 80–90 cubic feet of actual wood once you account for air gaps between pieces. A 'face cord' or 'rick' is typically one-third of a full cord and should not be confused with a full cord when comparing prices or BTU estimates.

Softwoods like pine, fir, and spruce have lower BTU per cord than hardwoods, but they ignite more quickly and can be useful for starting fires or shoulder-season heating. The main concern with softwoods is higher resin content, which can contribute to creosote buildup in chimneys if burned as a primary heat source. Mixing softwood for kindling with hardwood for sustained heat is a practical approach many people use.

Most hardwoods require 12–24 months of seasoning to drop below 20% moisture content under optimal drying conditions — split, stacked off the ground, with the top covered and sides open for airflow. Dense species like Oak and Hickory may need the full 2 years, while lighter hardwoods like Ash and Birch can season in 12 months. A moisture meter is the most reliable way to confirm your wood is ready to burn.

BTU values for firewood vary across sources because they depend on wood density, moisture content at the time of measurement, how tightly the cord is stacked, and regional variation within a species. Some charts report BTU for air-dry wood, others for oven-dry wood, and others at specific moisture percentages. This calculator uses widely cited per-cord values for seasoned firewood as a consistent baseline for comparison.