Board Feet Calculator
Enter lumber dimensions to calculate board feet. Build a project materials list, add a kerf waste allowance, and get a cost estimate at your entered price per board foot. Nominal vs. actual size guide included. Nothing uploaded.
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| Label | Length | Width | Thick | Qty | BF |
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Learn more: board feet and lumber calculations
The formula: from dimensions to board feet
Board feet = (thickness in inches x width in inches x length in inches) / 144. A 2x4 that is 8 feet long calculates as (1.5 x 3.5 x 96) / 144 = 3.5 board feet. This formula assumes you are using actual dressed dimensions, not the nominal size marked on the lumber.
Nominal vs actual lumber sizes
Nominal size is the name of the lumber as sold: 2x4, 1x6, 4x4. Actual size is the physical dimension after the lumber is dried and planed smooth. A nominal 2x4 is actually 1.5 inches x 3.5 inches. The calculator includes presets for all standard sizes, but for custom lumber always measure the actual dimensions rather than assuming nominal.
Building a project materials list
Enter each board in your project with its species or label, length, width, thickness, and quantity. The calculator totals all board feet across every piece. This helps you know exactly how much to order before visiting the timber yard, avoiding both under-ordering (which risks a second delivery from a different batch with colour mismatch) and over-ordering (which wastes expensive materials).
Kerf waste and sawing loss
The kerf is the width of material removed by a saw blade during each cut - typically 1/8 inch (3mm) for standard circular saw blades. When ripping multiple pieces, the kerf waste accumulates. Add 5-10% to your board feet total to account for this loss plus any rough crosscut allowances. The calculator has a kerf waste percentage field to adjust for your specific sawing method.
FAQ
How do I calculate board feet?
Board feet = (thickness in inches x width in inches x length in inches) / 144. For example, a 2x4 that is 8 feet long: (1.5 x 3.5 x 96) / 144 = 3.5 board feet. Always use actual dimensions, not nominal.
What is the difference between nominal and actual lumber size?
Nominal size is the name of the lumber (2x4, 1x6) as sold. Actual size is the physical dimension after the lumber is dried and planed smooth. A nominal 2x4 is actually 1.5 inches x 3.5 inches. Board feet calculations must always use actual dimensions for accuracy.
What is kerf waste in woodworking?
The kerf is the width of material removed by a saw blade during each cut - typically 1/8 inch (3mm) for standard circular saw blades. When ripping multiple pieces, the kerf waste accumulates. Adding 5-10% to your board feet total accounts for this loss plus any rough crosscut allowances.