Board feet to linear feet
There is no conversion factor between board feet and linear feet, because one measures volume and the other measures length. The factor only exists once you name the cross-section: a 2×4 has 0.667 board feet per linear foot, a 2×12 has 2.0.
Your profile
Common profiles
| Profile | bf per lf | lf per bf |
|---|
How this is calculated
- Board feet per piece = nominal thickness × nominal width × length ÷ 12.
- Board feet per linear foot = thickness × width ÷ 12. This is the only number that converts between the units, and it changes with every profile.
- Linear feet = pieces × length. It does not care about thickness or width at all.
Worked example
Ten 2×8 at 12 ft:
- bf per lf = 2 × 8 ÷ 12 = 1.333
- Total lf = 10 × 12 = 120 lf
- Total bf = 1.333 × 120 = 160 bf — which also matches 10 × 16 bf per piece
- Reverse: 200 bf at this profile is 200 ÷ 1.333 = 150 lf
Why the units get confused
Decking is sold by linear foot and hardwood by board foot, and both are "12 ft long". A customer who needs 120 linear feet of 5/4×6 decking and converts it to 66 board feet, then orders 66 board feet of hardwood, will receive 55 linear feet — because the hardwood is a different profile with a different multiplier. The units are not the problem; dropping the cross-section is.
The same confusion runs the other way in estimating. A takeoff measured in linear feet looks comparable between two suppliers until one quotes a 2×6 and the other a 5/4×6, at which point the linear-foot totals are identical and the material is not.
What a unit conversion cannot fix
- It does not add waste. Add your allowance to the linear feet before converting, because waste is a length problem, not a volume one.
- It does not handle mixed profiles. A deck with 5/4×6 field boards and 2×6 fascia is two calculations.
- It uses nominal dimensions only. That is what board feet mean. If you want actual volume in cubic feet, use the weight calculator, which does that conversion.
- It does not price by the piece. If the yard sells a 2×8×12 for $18 flat, per-board-foot pricing is a derived number and the yard may round it.
Questions people actually ask
How many linear feet are in a board foot?
It depends entirely on the cross-section. One board foot is 1/1.333 = 0.75 linear feet of 2×8, but 1.5 linear feet of 2×4. There is no universal factor.
Why does the lumber yard quote board feet for 2x material?
Most yards quote dimensional softwood by the piece and reserve board feet for hardwood, but the invoice often shows both, because board feet are how the mill sold it. The number to check is the piece count.
Is a 5/4x6 deck board 6 inches wide?
No — 5½ inches. It is also 1 inch thick, not 1¼. So a 12 ft board is 5.5 board feet nominal at 5/4×6 pricing conventions, but covers 5.5 square feet of deck.
How do I convert a square-foot deck area to linear feet of decking?
Divide the area by the coverage width of one row in feet, then multiply by the run length. In practice it is easier to count rows — that is what the deck board calculator does, and it avoids a conversion that hides the gap.