Firewood Calculator
Accurately estimate cord volume, weight, and BTU output for your wood stack.
1.00 Cords
128.00 cu ft
3,500 lbs
24.0 Million BTU
Volume Comparison: Your Stack vs. Standards
Comparison of your stack volume (cu ft) against a Full Cord and a Face Cord (16″ logs).
What is a Firewood Calculator?
A firewood calculator is an essential tool for homeowners, campers, and wood-burning enthusiasts to accurately determine the quantity of wood they have or need. Firewood is traditionally sold by the “cord,” but because wood stacks come in various shapes and sizes, simply looking at a pile isn’t enough to know if you’re getting what you paid for. Using a firewood calculator helps translate dimensions like length, height, and depth into a standardized unit of measurement.
Common misconceptions include the idea that a “truckload” is equivalent to a cord. In reality, most standard pickup trucks hold only a fraction of a full cord. By using this tool, you can ensure you have enough fuel for the winter and avoid being overcharged by suppliers.
Firewood Calculator Formula and Mathematical Explanation
The core calculation for a firewood calculator relies on cubic volume. A “Full Cord” is mathematically defined as 128 cubic feet of tightly stacked wood.
The standard formula used is:
Total Cords = (Length × Height × Depth) / 128
| Variable | Meaning | Unit | Typical Range |
|---|---|---|---|
| Length | The side-to-side span of the stack | Feet | 4 ft – 24 ft |
| Height | The ground-to-top measurement | Feet | 2 ft – 6 ft |
| Depth | The thickness of the stack (log length) | Feet | 1 ft – 4 ft |
| Density | Weight based on wood species | lbs/cord | 2000 – 4500 lbs |
Table 1: Input variables used by the firewood calculator to determine total volume and energy content.
Practical Examples (Real-World Use Cases)
Example 1: Buying a Face Cord
You find a seller offering a “Face Cord” of Red Oak. The stack is 8 feet long, 4 feet high, and the logs are cut to 16 inches (1.33 feet) deep.
Inputs: 8L x 4H x 1.33D = 42.56 cubic feet.
Calculation: 42.56 / 128 = 0.33 Cords.
The firewood calculator confirms that a face cord of 16″ logs is exactly one-third of a full cord.
Example 2: Filling a Wood Shed
Your wood shed measures 12 feet long, 6 feet high, and you stack it 4 feet deep with Birch.
Inputs: 12L x 6H x 4D = 288 cubic feet.
Calculation: 288 / 128 = 2.25 Cords.
Using the firewood calculator, you know to order 2.25 cords to fill your storage space completely.
How to Use This Firewood Calculator
- Measure the Length: Use a tape measure to find the total horizontal length of your wood stack in feet.
- Measure the Height: Measure from the bottom of the stack to the highest point. If the stack is uneven, take an average.
- Determine the Depth: Measure the length of the individual logs. Common lengths are 12″, 16″, or 24″. Convert these to feet (e.g., 16 inches = 1.33 feet).
- Select Wood Species: Choose the type of wood to get an estimated weight and BTU output.
- Review Results: The firewood calculator will instantly show you the total cords, cubic feet, weight, and energy value.
Key Factors That Affect Firewood Calculator Results
- Stacking Tightness: The 128 cubic foot rule assumes wood is “well-stacked.” Loose piles or “thrown” wood can contain up to 50% air, significantly reducing actual wood volume.
- Moisture Content: Freshly cut “green” wood weighs nearly twice as much as seasoned wood. Our firewood calculator assumes a seasoned state (~20% moisture).
- Wood Species Density: Hardwoods like Oak are much denser than softwoods like Pine, meaning a cord of Oak provides much more heat.
- Seasoning Time: Wood must dry for 6-12 months to reach maximum BTU efficiency. Unseasoned wood uses its energy to evaporate water rather than heating your home.
- Log Shape: Split wood stacks more tightly than round logs, leading to more actual wood fiber per cubic foot.
- Bark Thickness: Species with thick bark (like Hemlock) might show higher volume in a firewood calculator, but have slightly less usable wood fiber.
Frequently Asked Questions (FAQ)
A full cord of wood is exactly 128 cubic feet. This is traditionally a stack 4 feet high, 4 feet deep, and 8 feet long.
A face cord is a stack 4 feet high and 8 feet long, but only one log deep. The depth is usually 16 inches, making it 1/3 of a full cord.
Yes, the standard 128 cu ft measurement includes the air gaps naturally occurring in a neat stack. If the wood is loosely thrown, you should subtract about 30% from the result.
A cord of seasoned White Oak weighs approximately 3,500 to 4,000 lbs. Green Oak can weigh over 5,000 lbs.
Volume doesn’t equal dryness. If the wood hasn’t seasoned (dried), it will smoke regardless of how many cords the firewood calculator says you have.
A “Bush Cord” is just another regional name for a “Full Cord” (128 cubic feet).
A standard 8-foot pickup truck bed filled to the rails is roughly 1/2 of a cord (approx 64 cubic feet).
No, volume is purely based on space. However, wood type heavily affects the weight and BTU results in the firewood calculator.
Related Tools and Internal Resources
- Energy Efficiency Tips – Learn how to maximize your wood heat.
- Home Heating Guide – Comparing wood vs. gas vs. electric heating.
- Wood Stove Maintenance – Keep your chimney safe and clean.
- Lumber Calculator – For construction and DIY projects.
- Winter Preparedness Checklist – Essential steps for the cold season.
- Sustainable Forestry Practices – How to harvest wood responsibly.