Firewood Calculator
Cords Needed
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Estimated Cost
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Approximate Weight (lbs)
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How Firewood Heating Works
Firewood heating is the process of burning seasoned wood to produce heat for residential spaces, measured in British Thermal Units (BTU) per cord. According to the EPA's Burn Wise program, approximately 11.5 million U.S. households use wood as a primary or secondary heating fuel, making it one of the oldest and most widely used renewable energy sources. The amount of firewood needed depends on home size, climate zone, heating appliance efficiency, wood species, and whether wood is the primary or supplemental heat source. A well-insulated 2,000 square foot home using a modern EPA-certified wood stove typically burns 3-7 cords per heating season depending on climate severity.
Wood heating offers several advantages: it is a renewable resource when sourced from sustainably managed forests, it provides heat during power outages, and it can significantly reduce heating bills in areas where firewood is abundant and affordable. However, wood burning also produces particulate matter and requires proper equipment maintenance. The EPA recommends using certified stoves and properly seasoned wood to minimize emissions. Use our cubic feet calculator to verify firewood volume when purchasing from a dealer.
How Firewood Needs Are Calculated
The basic formula for estimating firewood needs is: Cords Needed = Base Cords for Climate x (Home Size / 2,000 sq ft) x Heating Source Multiplier. The base cords value represents the typical consumption for a 2,000 sq ft home in each climate zone: 3-5 for mild, 5-7 for moderate, and 7-9 for cold climates. The heating source multiplier is 1.0 for primary wood heat, 0.5 for supplemental (50% of heating), and 0.25 for occasional use.
Worked example: A 2,500 sq ft home in a moderate climate (base = 5 cords) using wood as the primary heat source. Cords needed = 5 x (2,500 / 2,000) x 1.0 = 6.25 cords. At $300 per cord for seasoned hardwood, that costs approximately $1,875 for the heating season. Each cord weighs roughly 3,000 lbs (varies by species), so you need to store about 18,750 lbs of wood -- plan for approximately 50 linear feet of stacking space at 4 feet high and 4 feet deep. Use our square footage calculator to plan your wood storage area.
Key Terms You Should Know
- Cord: The standard legal unit of firewood measurement, defined as a stack measuring 4 feet wide x 4 feet high x 8 feet long, totaling 128 cubic feet. Due to air gaps between logs, a cord contains about 80-90 cubic feet of solid wood.
- Face Cord (Rick): A stack that is 4 feet high x 8 feet long but only one row deep (typically 16 inches). A face cord is roughly one-third of a full cord. Terminology varies by region and is a common source of buyer confusion.
- BTU (British Thermal Unit): The standard measure of heat energy. One BTU equals the energy needed to raise 1 pound of water by 1 degree Fahrenheit. Hardwood cords produce 20-33 million BTU; softwood cords produce 14-21 million BTU.
- Seasoned Wood: Firewood that has been air-dried to a moisture content below 20% (ideally 15-20%). Properly seasoned wood burns more efficiently, produces less smoke, and minimizes creosote buildup compared to green (freshly cut) wood with 40-60% moisture.
- Creosote: A flammable tar-like substance that accumulates inside chimneys when wood burns incompletely, especially with green or wet wood. Creosote buildup is the leading cause of chimney fires, making annual chimney cleaning essential.
BTU Output by Wood Species
Not all firewood produces the same amount of heat. BTU output per cord varies dramatically based on wood density. Dense hardwoods pack more combustible material into the same volume, producing significantly more heat than softwoods. The table below compares common firewood species, with BTU data sourced from the Purdue University Cooperative Extension Service.
| Wood Species | Million BTU/Cord | Weight/Cord (lbs) | Splitting Ease | Spark Level |
|---|---|---|---|---|
| Osage Orange | 32.9 | 4,728 | Difficult | High |
| Shagbark Hickory | 27.7 | 4,327 | Moderate | Moderate |
| Black Locust | 26.8 | 4,016 | Difficult | Low |
| White Oak | 25.7 | 3,757 | Moderate | Low |
| Sugar Maple | 24.0 | 3,757 | Moderate | Low |
| Red Oak | 24.6 | 3,528 | Easy | Low |
| White Ash | 23.6 | 3,472 | Easy | Low |
| Douglas Fir | 20.7 | 2,970 | Easy | Moderate |
| Eastern White Pine | 14.3 | 2,236 | Very Easy | High |
Practical Examples
Example 1: Primary heat in a cold climate. A 1,800 sq ft home in Vermont using an EPA-certified wood stove as the sole heat source. Base estimate: 7 cords x (1,800/2,000) = 6.3 cords. Using white oak (25.7 million BTU/cord), that provides approximately 162 million BTU over the heating season. At $350/cord for seasoned oak, total cost is $2,205 -- compared to $3,000+ for propane or $2,800+ for heating oil in the same region.
Example 2: Supplemental weekend use. A 2,400 sq ft home in North Carolina with a gas furnace as the primary heat source and a fireplace insert for weekend ambiance and supplemental heat (25% of heating). Estimate: 3 cords (mild climate) x (2,400/2,000) x 0.25 = 0.9 cords. One cord of mixed hardwood at $250 plus delivery covers the entire season, providing cozy fires on 20-30 weekend evenings.
Example 3: Efficiency comparison. The same 2,000 sq ft home in Pennsylvania needs 12+ cords with an open fireplace (10-15% efficiency) but only 5 cords with an EPA-certified catalytic stove (80-85% efficiency). Switching from fireplace to stove saves 7 cords per year at $300/cord = $2,100 annual savings, paying for the stove ($1,500-$3,000) within 1-2 years.
Tips and Strategies for Firewood Heating
- Buy in spring, burn in winter. Purchasing firewood in spring or summer when demand is low yields better prices (20-30% savings) and allows additional drying time before the heating season begins.
- Split wood promptly after cutting. Split wood dries 2-3 times faster than rounds because more surface area is exposed to air. Split to 3-6 inch diameter pieces for optimal drying and burning.
- Invest in a moisture meter. A $20-$40 moisture meter eliminates guesswork about whether your wood is ready to burn. Target 15-20% moisture content for efficient, clean combustion.
- Upgrade to an EPA-certified stove. Modern EPA-certified stoves (70-85% efficiency) use 40-60% less wood than open fireplaces (10-15% efficiency). The investment pays for itself within 1-3 heating seasons.
- Stack at least 20 feet from your home. This prevents pest transfer (termites, carpenter ants) and reduces fire risk. Store wood off the ground and cover only the top for rain protection while allowing side ventilation.
- Buy local firewood only. The USDA recommends purchasing firewood within 50 miles of where you burn it to prevent spreading invasive pests like the emerald ash borer and spotted lanternfly.
Frequently Asked Questions
How much is a cord of firewood?
A full cord of firewood measures 4 feet wide x 4 feet high x 8 feet long, totaling 128 cubic feet. Prices vary by region and wood type, typically ranging from $200 to $400 per cord for seasoned hardwood. Green (unseasoned) wood costs 20-30% less but must dry for 6-12 months before burning efficiently. Delivery is usually extra at $50-$100 per load. Use our cubic feet calculator to verify the volume of wood you are purchasing.
What is the difference between a cord and a face cord?
A full cord is 4x4x8 feet (128 cubic feet). A face cord (also called a rick) is 4 feet high x 8 feet long but only one row deep, typically 16 inches (the length of a standard firewood log). A face cord is roughly one-third of a full cord. In many states, selling firewood in any unit other than the cord or fractions of a cord is illegal to prevent consumer fraud. Always clarify measurements when purchasing.
What type of wood burns the hottest?
Dense hardwoods produce the most heat per cord. Osage orange leads at approximately 32.9 million BTU per cord, followed by shagbark hickory (27.7 million BTU), eastern hornbeam (27.3 million BTU), black locust (26.8 million BTU), and white oak (25.7 million BTU). By comparison, softwoods like eastern white pine produce only about 14.3 million BTU per cord, meaning you need nearly twice as much softwood to generate the same heat.
How many cords of firewood do I need for winter?
For a 2,000 square foot home using wood as the primary heat source, plan on 3 to 5 cords in a mild climate, 5 to 7 cords in a moderate climate, and 7 to 9 cords in a cold northern climate. If wood is supplemental (50% of heating), halve those numbers. Homes with modern EPA-certified wood stoves are 20-30% more efficient than open fireplaces, requiring fewer cords for the same heat output.
How long does firewood need to season before burning?
Most hardwoods require 6 to 12 months of seasoning when split to 3-6 inch diameter pieces and stacked with good airflow. Softwoods season faster, typically 3 to 6 months. Properly seasoned firewood has a moisture content below 20%, verified with a moisture meter ($20-$40). Green wood with 40-60% moisture produces roughly 60% of the BTU output of seasoned wood, creates excessive smoke, and accelerates dangerous creosote buildup in chimneys.
How should I store firewood to prevent pests and rot?
Stack firewood at least 20 feet from your home to reduce pest transfer risk (termites, carpenter ants, bark beetles) and fire risk. Store wood off the ground on pallets, concrete blocks, or a gravel pad. Leave sides open for air circulation and cover only the top to shed rain. Never transport firewood long distances -- the USDA recommends buying within 50 miles to prevent spreading invasive pests like the emerald ash borer and spotted lanternfly.