Lumber Calculator
A deck project requiring 40 pieces of 2x6x12 ft lumber equals 480 board feet. At $3-$7 per board foot for pressure-treated lumber, materials cost $1,440-$3,360. That's approximately 40 boards at $8-$15 each for standard 2x6x12 PT.
Lumber Calculator
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How to Calculate Board Feet
Board foot = (thickness in inches x width in inches x length in feet) / 12. One board foot equals a piece 1 inch thick, 12 inches wide, and 1 foot long (144 cubic inches).
| Nominal Size | Actual Size | Board Feet per Linear Foot | Typical Price per Piece (8 ft) |
|---|---|---|---|
| 2x4 | 1.5 x 3.5 in | 0.667 | $4-$8 |
| 2x6 | 1.5 x 5.5 in | 1.0 | $6-$13 |
| 2x8 | 1.5 x 7.25 in | 1.333 | $8-$17 |
| 2x10 | 1.5 x 9.25 in | 1.667 | $12-$22 |
| 2x12 | 1.5 x 11.25 in | 2.0 | $16-$30 |
| 4x4 | 3.5 x 3.5 in | 1.333 | $10-$18 |
| Wood Type | Price per Board Foot | Best Use |
|---|---|---|
| SPF (framing) | $0.50-$1.50 | Framing, studs |
| Pressure-treated | $1.00-$2.50 | Decks, outdoor |
| Cedar | $3.00-$6.00 | Fencing, siding |
| Douglas fir | $2.00-$4.00 | Beams, structural |
| Oak (red) | $4.00-$8.00 | Furniture, flooring |
| Walnut | $8.00-$15.00 | Fine woodworking |
| Maple (hard) | $5.00-$10.00 | Cabinets, butcher block |
Tips
- Nominal lumber sizes (2x4) are larger than actual sizes (1.5x3.5 in) due to milling
- Hardwood lumber is sold in random widths and lengths; order 20% extra
- Check lumber for straightness by sighting down the edge before purchasing
- Pressure-treated lumber needs 3-6 months to dry before staining
- Big box stores price by the piece; lumber yards often price by the board foot
Frequently Asked Questions
What is a board foot?
A board foot is a unit of lumber volume equal to 144 cubic inches (1 inch thick x 12 inches wide x 12 inches long). It's the standard purchasing unit for hardwood and specialty lumber. One 2x6x12 ft board equals 12 board feet.
How do I calculate board feet?
Multiply thickness (inches) x width (inches) x length (feet), then divide by 12. For a 2x8x10 ft board: 2 x 8 x 10 / 12 = 13.33 board feet. Use nominal dimensions, not actual.
How much does lumber cost?
Framing lumber (SPF) costs $0.50-$1.50 per board foot. Pressure-treated runs $1-$2.50/BF. Cedar is $3-$6/BF. Hardwoods range from $4/BF (oak) to $15+/BF (walnut). Prices fluctuate with commodity markets.
What is the actual size of a 2x4?
A nominal 2x4 actually measures 1.5 x 3.5 inches. This is because lumber is measured before planing (smoothing). All standard dimensional lumber is 1/2 inch smaller per dimension: 2x6 = 1.5x5.5, 2x8 = 1.5x7.25.
How many 2x4s do I need for a wall?
For standard 16-inch on-center framing, divide wall length in inches by 16 and add 1 for the starting stud. A 12-foot wall needs 10 studs plus top plate (2), bottom plate (1), and extra for corners and headers.
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