Lumber Calculator
Calculate board feet and linear feet of lumber for framing, decking, and woodworking projects. Convert between board feet, linear feet, and pieces to price your lumber order accurately.
🌳 Framing🏗️ Board Feet = Thickness (in) x Width (in) x Length (ft) / 12
Board thickness (inches)
Board width (inches)
Board length (feet)
Number of boards
Price per board foot ($)
Please enter valid values.
Formula & Reference
| Variable | Formula | Units |
|---|---|---|
| Lumber Calculator | Board Feet = Thickness (in) x Width (in) x Length (ft) / 12 | board feet |
Step-by-Step Examples
Example 1
Wall Framing Studs
2x4 studs, 8 ft long, 20 studs, $0.80/BF.
- BF per stud = 2x4x8/12 = 5.33 BF
- Total = 5.33 x 20 = 106.7 BF
- Cost = 106.7 x $0.80 = $85.33
✓ 106.7 BF, ~$85
Example 2
Deck Boards
5/4x6 deck boards, 12 ft, 50 boards.
- BF per board = 1.25x6x12/12 = 7.5 BF
- Total = 7.5 x 50 = 375 BF
- 5/4x6 is the most common deck board size
✓ 375 BF
Example 3
Door/Window Headers
Double 2x10 header, 6 ft, 4 pieces.
- BF per piece = 2x10x6/12 = 10 BF
- Total = 10 x 4 = 40 BF
- Headers over openings require doubled members
✓ 40 BF
Real-World Applications
Framing Contractors
Estimate lumber quantities and costs before bidding residential projects.
Deck Builders
Calculate decking, joists, and beam lumber quantities.
DIY Projects
Price out lumber for room additions or sheds before buying.
Fence Builders
Calculate rail, picket, and post lumber for wood fences.
Common Mistakes to Avoid
⚠️
Confusing nominal and actual dimensions
A 2x4 is actually 1.5x3.5 inches. For board feet, use NOMINAL dimensions (the name on the tag), not actual. The lumber industry calculates BF from nominal size.
⚠️
Forgetting waste
Add 10-15% for framing waste (blocking, cripples, corners). Add 15-20% for decking so bowed boards can be discarded.
⚠️
Not matching species to price
Pine, Douglas fir, and pressure-treated lumber have different prices per board foot. Verify the species before quoting.
Frequently Asked Questions
What is a board foot? ▾
A unit of lumber volume: 1 foot wide x 1 foot long x 1 inch thick = 1 board foot. Formula: Thickness (in) x Width (in) x Length (ft) / 12.
Board feet vs linear feet? ▾
Linear feet measures length only. Board feet measures volume. A 2x4 stud 8 ft long is 8 linear feet but 5.33 board feet.
How many 2x4s for a wall? ▾
For a standard 8-ft wall with studs 16 inches on center: divide wall length in inches by 16, add 1, then add extra for corners (3 per corner) and doors (5 per opening).
What does pressure-treated lumber cost per BF? ▾
PT lumber typically runs 20-40% more than standard dimensional lumber. Ground-contact PT (UC4B) is required within 6 inches of soil.
How much does lumber weigh per BF? ▾
Roughly 2.5-4 lbs per BF. Dry framing lumber (SPF, DF): about 2.8 lbs/BF. This matters for structural loads and delivery planning.