Board Foot Calculator
Total board feet for a lumber order, one line per board size, with per-line and whole-order totals. The same unit prices spray foam coverage. Everything runs in your browser.
How to use
- Add a line for each board size in your order: thickness and width in inches, length in feet.
- Use nominal dimensions for rough-sawn lumber (a nominal 2 by 4 entered as 2 and 4) and finished dimensions for dressed or planed stock.
- Repeat the same line once and enter a quantity, or add one line per size; the total sums the whole list.
- Read board feet per line and the order total. Hardwood pricing runs per board foot, so compare the total against the yard's price. Keep about 10 percent extra stock for cupped boards and bad cuts.
How the math works
Board feet equal thickness in inches times width in inches times length in feet, divided by 12, because one board foot is 144 cubic inches. Each line computes its own board feet and the order total sums the lines, rounded once at the end so a long list does not collect rounding drift. Fractional dimensions are welcome: a 5/4 deck board is 1.25 inches thick.
The same unit measures spray foam coverage. One board foot of foam is one square foot at one inch thick, so a 600 board foot two-component kit, a typical closed-cell spec from makers like Touch 'n Seal, yields about 600 square feet at one inch or 300 at two.
Lumber is rarely as tame as its sticker. Keep roughly 10 percent more board footage than the total for warping, mis-cuts, and the board you split carrying it.
Frequently asked questions
Is my cutting list uploaded or stored anywhere?
No. The calculator runs entirely in your browser tab, and your list never leaves the page. Nothing is stored, nothing is sent to a server, and the page sets no cookies. Ad slots on the page are served by third-party networks, which follow their own privacy policies.
What exactly is a board foot?
A volume: one board foot is a piece 1 inch thick, 12 inches wide, and 1 foot long, or any combination that multiplies out to the same 144 cubic inches. The formula is thickness in inches times width in inches times length in feet, divided by 12. A 2 by 4 that is 8 feet long holds 5.33 board feet.
Nominal or finished dimensions?
Match what the seller prices by. Hardwood yards sell rough lumber by the board foot using nominal thickness quarters (4/4 is 1 inch, 8/4 is 2 inches) and the width as it comes off the saw, so enter those numbers. For planed lumber priced by finished size, enter the actual measured thickness and width instead. The math is the same; the choice changes what you pay for.
Why is spray foam sold in board feet?
Because board feet measure volume of coverage, and foam coverage is a volume: one board foot of foam covers one square foot at one inch thick. Kit makers rate yield that way; a typical two-component closed-cell kit like the Touch 'n Seal Foam Kit 600 is rated for 600 board feet, meaning about 600 square feet of foam at one inch, or 300 square feet at two inches. Enter a spray area as a 1 inch thick piece one foot wide and as many feet long to get its board feet.