Wood & Trim
Board Foot Calculator
Convert lumber dimensions into board feet and cost, per row and in total.
Enter your measurements
Results update as you type.
About this calculator
A board foot is a volume: 12 in × 12 in × 1 in, exactly one twelfth of a cubic foot. Enter thickness, width, length and quantity for each lumber row; the tool totals board feet and, with an optional price per board foot, the cost.
How to use this calculator
- Measure the thickness and width in inches and the length in feet.
- Enter one row per size, with the quantity of pieces.
- Add the price per board foot from your supplier if you want a cost.
- Calculate for per-row and total board feet.
Formula
Board feet = thickness (in) × width (in) × length (ft) ÷ 12
One board foot = 12 × 12 × 1 in = 1/12 ft³ = 144 in³
Total = sum of rows; cost = total × price per board foot
Assumptions
- Any supported unit is converted exactly before the formula runs.
- Rough (not surfaced) lumber measurement; the formula is definitional.
- Cost uses the unrounded total, rounded half-up to cents.
Board-foot reference
| Dimensions (thickness × width × length) | Volume |
|---|---|
| 1 in × 12 in × 1 ft | 1 board foot |
| 2 in × 6 in × 8 ft | 8 board feet |
| 1.5 in × 3.5 in × 8 ft | 3.5 board feet |
Directly computed from dimensions. Billing may use a different nominal or rough-lumber basis.
Common mistakes
- Mixing nominal and actual dimensions in one volume estimate.
- Entering feet in a field set to inches.
- Assuming a supplier bills on the same finished-dimension basis.
Worked example
Try it: press “Load example” above the form.
Two 1×6×8 ft boards are 4 BF each, 8 BF total.
Limitations
A board foot is volume, not area or length — it cannot be compared directly with square feet.
Frequently asked questions
What is one board foot?
A board foot is a volume equal to a board 12 in long, 12 in wide and 1 in thick. Calculate thickness × width × length in inches, then divide by 144.
Should I enter nominal or actual lumber dimensions?
Enter the dimensions on the basis your supplier uses for pricing. Nominal sizes and finished dressed dimensions differ. This tool multiplies the dimensions you provide; it does not choose a grading or billing convention.
What does the worked example show?
Two 1×6×8 ft boards are 4 BF each, 8 BF total.
Which assumptions should I check before using the result?
A board foot is volume, not area or length — it cannot be compared directly with square feet.
Sources
Sources explain the methods and any named product presets. Check your product label where coverage, yield or density differs.
Calculation documentation · Updated 2026-11-08 · Version 1.6.4. Estimates are planning aids. Confirm quantities, coverage and prices with your supplier before purchasing. Found an error? Report it.
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