Firewood Cord Calculator
Calculate seasoned vs green firewood weight, million BTU heat content, and heating oil equivalents for cords of firewood.
Equivalent to ~371 gallons of #2 heating oil
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What Is a Firewood Cord Calculator?
A firewood cord calculator computes the total thermal heating energy in million BTUs (British Thermal Units) and weight of seasoned firewood cords. It allows homeowners to compare wood heating costs directly against heating oil, natural gas, and propane.
How to Use This Calculator
- Enter number of full cords (128 cu ft).
- Select the wood species (Oak, Hickory, Ash, Maple, Birch, or Pine).
- View the total million BTUs of thermal energy.
- Review the equivalent gallons of #2 heating oil and seasoned vs green weights.
Thermal Cord Heating Value
\text{Total BTU} = \text{Cords} \times \text{BTU}_{\text{species}}, \quad \text{Oil Equivalent (gal)} = \frac{\text{Total BTU}}{138,500}One gallon of #2 home heating oil contains ~138,500 BTUs. High-density hardwoods like Hickory produce ~28.5 Million BTU per cord (~205 gal oil equivalent).
Worked Example
Scenario: Burning 3 cords of seasoned White Oak in a high-efficiency wood stove.
Oak heating value: 25.7 Million BTU per cord.
Total energy: 3 cords × 25.7M = 77.1 Million BTU.
Equivalent heating oil: 77,100,000 ÷ 138,500 = 556.7 gallons of heating oil.
Seasoned weight: 3 × 3,800 lbs = 11,400 lbs (5.7 tons of wood).
Tips & Key Notes
- Burning unseasoned wet wood wastes up to 30% of its potential heat energy simply boiling away internal moisture inside the firebox.
- Dense hardwoods (Oak, Hickory, Beech) provide long-lasting overnight coals, while softwoods (Pine, Fir) ignite quickly for kindling.
- Clean your chimney flue annually to eliminate creosote glaze build-up and prevent chimney fires.
Frequently Asked Questions
Which firewood produces the most heat per cord?
Osage Orange (32.9M BTU), Shagbark Hickory (28.5M BTU), Black Locust (27.9M BTU), and White Oak (25.7M BTU) produce the highest heat output per cord in North America.
How many gallons of heating oil equal one cord of oak?
One cord of seasoned oak produces approximately 25.7 million BTUs, equivalent to about 185 to 190 gallons of home heating oil.
How can you tell if firewood is seasoned enough to burn?
Seasoned firewood has radial cracks (checks) at the log ends, loose bark, a lighter hollow "clunk" sound when two logs are tapped together, and a moisture reading under 20% on a pin meter.
How much does a cord of wet green oak weigh?
A cord of freshly cut green oak weighs up to 5,500 pounds (2.75 tons). When fully seasoned, its weight drops to around 3,800 pounds.
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