Board Foot Calculator
Calculate board feet for one lumber size with explicit actual or nominal dimensions.
Calculations run locally in your browser. Inputs are not transmitted or attached to analytics.
What the single-size calculator measures
This calculator measures the geometric volume of one repeated lumber size. Thickness and width are entered in inches, length in feet, and quantity as a whole number. Select actual when the dimensions came from a measurement; select nominal when the figures are trade labels or quoted nominal sizes. The selection is retained beside the answer but does not silently alter a number you typed.
The calculation is thickness × width × length × quantity ÷ 12. Division by twelve reconciles the two inch dimensions with a length stated in feet. The result panel reports both the per-piece value and the row total so a user can distinguish a large board from a large quantity.
Worked example: four wide shelf boards
Four boards measuring 1.125 inches thick, 11 inches wide and 7 feet long contain 28.875 board feet: 1.125 × 11 × 7 × 4 ÷ 12. Each board contributes 7.21875 BF. A two-decimal display may show 28.88 BF, but the copy text preserves the entered dimensions and the calculation basis so the rounded figure is not detached from its working.
Actual and nominal are declarations, not conversions
Choosing nominal is useful when checking a quotation written in nominal sizes, but the calculator still multiplies the numbers shown. It does not assume that 2 × 6 means 1.5 × 5.5, because dressed sizes vary by product, surfacing, moisture and market. For physical volume, measure the board or enter a separately documented actual size. For comparison, use the nominal-versus-actual tool.
Input and result checks
Blank, zero, negative, non-finite and overflowing dimensions are rejected. Quantity must be a positive safe integer. Before relying on the result, confirm that both cross-section dimensions use inches, length uses feet, every piece really shares the same dimensions, and the basis label matches the source of the numbers.
- Measure at the point required by the transaction.
- Keep display rounding separate from contractual tally rounding.
- Use mixed tally when any row has a different size or basis.
Questions about this topic
Can I enter fractional inches as decimals?
Yes. Convert the fraction accurately, such as 1¼ to 1.25, and retain the original measurement with the result.
Does nominal mode change my inputs?
No. It labels the basis only; no trade-size substitution occurs.
Can this determine structural capacity?
No. It measures volume, not grade, species strength, span or load capacity.
Related BoardFoot Bench pages
Method and content reviewed 3 September 2026.