About {b}
Why board foot calculators disagree with each other
A board foot is a volume: 144 cubic inches of rough lumber, the equivalent of a piece one inch thick, twelve inches wide and twelve inches long. The formula is simple — thickness in inches × width in inches × length in feet ÷ 12 — but two things trip people up, and different calculators handle them differently.
The first is nominal versus actual dimensions. A board sold as 4/4 ("four-quarter", one inch) usually measures about 13/16" after surfacing, but the yard charges footage on the rough inch it was sawn at. A calculator that uses your caliper measurement will quietly under-count what you are billed for. BoardsCalc uses nominal dimensions, matching lumber-industry practice.
The second is the quarters system itself: 4/4 = 1", 5/4 = 1¼", 6/4 = 1½", 8/4 = 2", 12/4 = 3". Hardwood is quoted this way and most calculators make you convert it yourself.
What BoardsCalc does differently
- It accepts fractions the way woodworkers write them. Type
3/4,1 1/2or1-1/2and it parses correctly — no converting to decimals in your head at the lumber rack. - One-tap quarters. Buttons for 4/4 through 12/4 enter the right thickness for you.
- It builds a cut list, not just one answer. Add each board type with its own quantity and price, name them, and get project totals — because real projects are never one board.
- Waste is built in. Knots, checks, snipe and off-cuts mean nobody uses 100% of a board. Set your allowance and the total becomes the number you actually take to the yard.
- Printable. The cut list prints as a clean sheet with the calculator interface stripped out, so you can hand it across the counter.
- Metric and imperial. Work in centimetres if your stock is European, and see cubic metres alongside board feet either way (1 m³ ≈ 423.78 BF).
- Nothing is uploaded. No account, no server. It runs entirely in your browser, and your cut list stays on your device.
How the numbers are produced
Each line computes thickness × width × length ÷ 144 with lengths normalised to inches, or true volume in cubic metres when working metric, converted at the exact factor (1 board foot = 0.00235973722 m³). Quantities multiply per line; costs use your price per board foot; the waste allowance scales the project total rather than individual lines.
The arithmetic is covered by an automated test suite that verifies the canonical definitions (1" × 12" × 1 ft = 1 BF, 2 × 6 × 8 ft = 8 BF), thousands of randomly generated fraction inputs against ground-truth arithmetic, project additivity, and metric–imperial equivalence.
What is deliberately excluded
The waste allowance is a blunt instrument by design: it does not model saw kerf, joinery losses, grain matching or defect distribution in a specific board, all of which vary by project and by the stock in front of you. Moisture content and shrinkage are not modelled. Sheet goods sold by the square foot (plywood, MDF) are a different unit and are not board-footed. Treat every figure as an estimate to check against your supplier's quote.
Independence
BoardsCalc is an independent tool with no affiliation to any lumber supplier, retailer or manufacturer, and no commission on what you buy.
What is coming
More shop maths in the same style: filament and print-cost calculators, sheet-goods yield, glue-up and clamping pressure, feeds and speeds, and species-specific price references.