Board foot calculator
A board foot is 144 cubic inches of sawn timber: thickness × width × length in inches, divided by 144. A 1×12 one foot long is one board foot, and so is a 2×6 one foot long. It measures volume, which is why a length in feet on its own can never answer it.
How to use the board foot calculator
The trap is nominal versus actual. Timber sold as a two-by-four is not two inches by four; it is milled to about 1.5 by 3.5 inches after drying and planing. An eight-foot 2×6 therefore bills as 8 board feet and measures 5.5. Yards quote on the nominal size by convention rather than to overcharge, but it does mean that measuring your own boards and calculating from those will never reconcile with the invoice, and you have to decide up front which of the two numbers you are after.
Hardwood is quoted differently again, in quarters of an inch of thickness: 4/4 is one inch, 5/4 is an inch and a quarter, 8/4 is two. Width is taken at the narrow end of a board that is rarely parallel-sided, and the length is rounded down to the foot, so two boards sold as the same board footage can differ noticeably in usable wood. Rough-sawn stock is the one case where nominal and actual nearly agree, which is part of why it costs less per board foot and part of why it is worth the planing.
What people use it for
- Checking a timber yard quote before paying it
- Pricing a hardwood order sold in quarters
- Costing the offcuts left over from a build
- Comparing rough-sawn against planed stock on the same basis
- Converting a cubic-metre price into board feet to compare suppliers
Questions
Multiply thickness, width and length in inches and divide by 144. An eight-foot 2×6 is 8 board feet on its nominal size, and 5.5 on the size it actually mills out to.
Nominal to check a quote, because that is what yards bill on. Actual if you want to know how much wood is in front of you.
No. It is a volume: 144 cubic inches, or a piece one inch thick, twelve wide and twelve long.
Thickness in quarters of an inch. 4/4 is one inch, 5/4 an inch and a quarter, 8/4 two inches. It is the thickness before planing.
About 424. A board foot is roughly 0.00236 cubic metres.
Convert to inches first. Board feet are an imperial unit and metric yards sell by the cubic metre.