About Lumber Calculator
Calculate board feet of lumber for any project. Enter thickness, width, and length to get total board footage, pricing estimates, and common lumber size conversions. Free.
How to use
- Enter the lumber dimensions: thickness, width, and length for each piece. Lumber is sold by nominal dimensions (2x4, 2x6) but the actual dimensions are smaller. A nominal 2x4 actually measures 1.5 x 3.5 inches. The calculator uses actual dimensions for accurate board footage calculations.
- Set the quantity of boards you need. If your project requires 24 pieces of 2x6x8, enter those dimensions once and set the quantity to 24. The calculator multiplies by quantity automatically to give you the total board footage for that lumber size.
- View the total board footage calculated automatically. Board footage is the standard lumber measurement unit: one board foot equals a piece 1 inch thick, 12 inches wide, and 12 inches long (144 cubic inches). A single 2x6x8 is 8 board feet. Understanding board feet helps you compare prices across different lumber dimensions.
- Check pricing estimates based on common lumber species: SPF (spruce-pine-fir) is the most affordable at $3-$6 per board foot, pressure-treated SPF costs $4-$8, cedar runs $6-$12, and hardwoods like oak or maple cost $8-$20+ depending on species and grade.
- Add multiple lumber sizes to build a complete project material list. A typical deck framing package might include 4x4 posts, 2x8 beams, 2x6 joists, and 5/4x6 decking — enter each size separately and the calculator provides a combined total with pricing for the entire project.
- Print or export your lumber list for the hardware store. Having exact quantities and dimensions prevents overbuying (wasted money) and underbuying (extra trips). Most lumber yards can cut to length if you provide exact measurements.
Frequently asked questions
How do you calculate board feet?
Board feet = (Thickness in inches x Width in inches x Length in feet) / 12. Example: a 2x6x10 piece = (2 x 6 x 10) / 12 = 10 board feet. For nominal lumber dimensions, use the nominal sizes in the formula (not actual sizes) when purchasing, as lumber is priced by nominal board footage. However, for project planning and material volume calculations, use actual dimensions: a 2x6 actually measures 1.5 x 5.5 inches. This calculator handles both conversions and shows you actual volume as well as nominal board footage for purchasing purposes.
What is the actual size of a 2x4?
A nominal 2x4 actually measures 1.5 x 3.5 inches (38 x 89 mm). The difference is due to milling, planing, and drying after the rough-cut stage. Common actual sizes: 1x4 = 0.75 x 3.5 inches, 2x4 = 1.5 x 3.5, 2x6 = 1.5 x 5.5, 2x8 = 1.5 x 7.25, 2x10 = 1.5 x 9.25, 2x12 = 1.5 x 11.25, 4x4 = 3.5 x 3.5, 6x6 = 5.5 x 5.5. This distinction matters when designing structures — a wall framed with 2x4 studs provides only 3.5 inches of cavity depth for insulation, not 4 inches.
How many 2x4s do I need for framing?
For standard wall framing with studs at 16 inches on centre: divide the wall length in inches by 16, add 1 for the end stud, plus additional studs for corners, intersecting walls, and window/door framing. A 20-foot wall requires about 16 studs, plus a doubled top plate (two 2x4x10 pieces per 20 feet) and a bottom plate (one 2x4x10 per 20 feet). King studs, jack studs, and cripple studs around openings add 4-8 additional 2x4s per opening. A rough estimate for a full room: wall length in feet x 0.8 = approximate number of 8-foot 2x4 studs needed, plus 15% for plates and waste.
What does linear foot vs board foot mean?
A linear foot (or running foot) measures only length — one linear foot of 2x4 is simply 12 inches of 2x4 regardless of its width and thickness. A board foot measures volume — one board foot is 144 cubic inches (1 inch thick x 12 inches wide x 12 inches long). One linear foot of 2x4 equals 0.667 board feet, while one linear foot of 2x12 equals 2 board feet. Linear feet are used for purchasing trim, moulding, and decking. Board feet are used for pricing dimensional lumber and hardwoods. Knowing the difference prevents costly ordering mistakes.
How much does lumber cost per board foot?
Prices fluctuate with market conditions but typical ranges in Canada: SPF construction lumber $3-$6/board foot, pressure-treated SPF $4-$8/board foot, western red cedar $6-$12/board foot, Douglas fir $5-$9/board foot, domestic hardwoods (oak, maple, cherry) $8-$20/board foot, exotic hardwoods (walnut, teak, mahogany) $15-$40+/board foot. Lumber prices experienced extreme volatility in 2021-2023 (SPF peaked at $1,700 per thousand board feet versus the historical average of $350-$450). Current prices have stabilized but remain above pre-pandemic levels. Check current pricing at your local supplier before budgeting.
What is the best lumber species for outdoor projects?
For Canadian outdoor projects: pressure-treated SPF is the most cost-effective for ground contact and structural applications. Western red cedar offers natural rot and insect resistance with beautiful grain, ideal for decking, fencing, and siding where appearance matters. Ipe (Brazilian hardwood) is extremely durable (25+ year lifespan) but expensive and difficult to work with. For ground-contact applications (posts, garden beds), use lumber rated for ground contact (UC4A or UC4B preservative rating). Standard pressure-treated lumber is rated for above-ground use only (UC3B). Always check the treatment stamp to ensure the correct rating for your application. For a complete deck project budget including all materials and labour, use the
Deck Cost Estimator.
How much waste should I factor into lumber orders?
Add 10-15% to your calculated requirements for waste, defects, and cutting losses. For projects with many angle cuts (roof framing, deck boards at 45 degrees), increase to 15-20%. For hardwood projects where grain matching matters, add 20-25%. When buying from a lumberyard, inspect each board for warping, cupping, twisting, large knots, and split ends — cull defective boards before purchasing. For pre-cut lengths from hardware stores, waste is primarily from end cuts and defects. Buying longer boards and cutting to length gives you more flexibility but generates more waste than buying exact lengths.
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