Calculator
Board Feet Calculator
Board feet and linear feet are not interchangeable, and lumber is priced by the board foot for a real reason: it accounts for a board's full volume (thickness x width x length), not just its length. A thick, wide board and a thin, narrow board of the same linear length contain very different amounts of actual wood, and board-foot pricing captures that difference where a linear-foot price wouldn't.
This calculator converts lumber dimensions and quantity to board feet using the standard formula, with a worked example showing how the two units diverge as thickness and width change. See board feet explained for more worked examples.
Calculate your quantity
Total board feet
4 bd ft
- Board feet per board
- 4 bd ft
Shopping summary
- • 1 board(s), 4 bd ft total
This is an estimate — confirm structural work with a professional.
How this calculation works
Board feet = (thickness in inches x width in inches x length in feet) / 12. So a single board 1 inch thick, 6 inches wide, and 8 feet long is (1 x 6 x 8) / 12 = 4 board feet — notice that the calculation already 'knows' the board is 8 linear feet long, but reports 4 board feet, because board feet measures volume, not length. A thicker or wider board of the same 8-foot length would report proportionally more board feet even though its linear length hasn't changed at all.
This matters practically because a project's lumber list often mixes board sizes — framing lumber, trim stock, and a dimensional beam all measured and priced by board foot lets you compare true material cost across different board sizes on an apples-to-apples basis, which a simple linear-foot total across mixed sizes can't do.
Common mistakes
- Treating board feet and linear feet as the same unit when comparing prices or totaling a cut list — they diverge as soon as board thickness or width differs between pieces.
- Forgetting that nominal lumber dimensions (a '2x4') aren't the actual dressed dimensions (closer to 1.5 x 3.5 inches) — board-foot calculations for pricing typically use nominal size by convention, but actual dressed size matters for fit and structural calculations.
- Not accounting for kerf loss (the width of material lost to each saw cut) when planning a cut list from larger stock, which is separate from the board-foot total of the raw material purchased.
- Buying rough-sawn hardwood board footage without budgeting extra for planing/surfacing loss, since a rough board loses real thickness once milled flat and smooth on both faces.
- Not grouping similar-length cuts together when planning which stock board to buy for each, which can mean paying for and wasting more total board feet than a slightly more planned cut layout would use.
Shopping summary
Total board feet needed across your full cut list (summing thickness x width x length / 12 for each piece), then buy stock lengths that minimize waste against your actual cut list, rather than ordering the exact board-foot total in mismatched odd lengths.
Worked example: a project needs four pieces at 1x6x8 (4 board feet each = 16 total) and two pieces at 2x8x10 ((2x8x10)/12 = 13.3 board feet each = 26.6 total), for a project total of about 42.6 board feet — buying to that combined total is more accurate than pricing the two different board sizes as if they were interchangeable linear footage.
FAQ
Is a board foot the same as a linear foot?
No — a linear foot is simply length; a board foot is a volume measure (thickness x width x length / 12), so two boards of the same linear length but different thickness or width contain a different number of board feet, and lumber is priced accordingly.
Why does lumber pricing use board feet instead of linear feet?
Because board feet accounts for the actual volume of wood in a piece, which is what determines how much material (and cost) went into milling it — pricing by linear foot alone would charge the same for a thin narrow board and a thick wide one of equal length, which doesn't reflect the real material difference.
Do I need to convert board feet to weight for shipping estimates?
Only if ordering from a supplier that ships by weight rather than local pickup — board feet and weight aren't directly interchangeable either, since wood species density varies (a board foot of oak weighs meaningfully more than a board foot of pine), so weight-based shipping quotes need the specific species' density, not just the board-foot total.
What standard lengths does dimensional lumber usually come in?
Common stock lengths run 8, 10, 12, 16, and sometimes 20 feet, though availability varies by species and supplier — planning a cut list around these standard lengths before calculating total board feet reduces both waste and the number of separate pieces you need to buy.