Calculate board feet, lumber volume, quantity, waste allowance and estimated cost from lumber dimensions. Add multiple board sizes to price an entire project.
Calculator settings
Choose the dimension system and lumber measurement method.
Lumber details
Add every lumber size included in the project.
| Thickness | Width | Length | Quantity | Price / BF |
|---|
Waste and project cost
Allow for cutting, defects and other material losses.
Calculation results
Your lumber volume, quantity and cost estimate.
Calculation breakdown
What is a board foot?
A board foot is a lumber volume measurement equal to a board measuring 1 inch thick, 12 inches wide and 1 foot long. Lumber sellers commonly use board feet when pricing and estimating hardwood and other dimensional stock.
The calculator above applies the same volume relationship while allowing multiple lumber sizes, quantities, waste allowance and project pricing.
How to calculate board feet
Use these steps for a single lumber size:
- Enter the lumber thickness in inches.
- Enter the lumber width in inches.
- Enter the board length in feet.
- Enter the number of boards.
- Multiply the dimensions and divide by 12.
- Multiply the board-foot result by the number of boards.
Board feet example
Suppose you have ten boards measuring 2 inches thick, 8 inches wide and 10 feet long.
13.33 × 10 = 133.33 BF total
With a 10% waste allowance, the purchasing estimate becomes about 146.67 board feet.
Nominal vs actual lumber dimensions
Nominal lumber sizes describe the traditional name of a board, while actual dimensions describe the measured finished size. For example, a board sold as 2 × 4 often has smaller actual dimensions after drying and surfacing.
For accurate material estimation, use the actual dimensions when they are known. If your supplier prices stock using nominal dimensions, select the appropriate measurement method and use the dimensions relevant to the supplier's pricing system.
Board feet and cubic feet
One board foot represents 1/12 of a cubic foot. Therefore:
Cubic feet = Board feet ÷ 12
The calculator also converts the lumber volume to cubic metres for projects using metric volume measurements.
How much lumber should I buy?
Start with the calculated board-foot requirement and add a suitable waste allowance. The appropriate allowance depends on the project, lumber quality, cutting pattern and amount of unusable material.
- 5% waste: Simple work with efficient cuts and good stock.
- 10% waste: A common planning allowance for many projects.
- 15% or more: More complex cutting, defects, short pieces or difficult layouts.
Waste percentages are planning allowances rather than guarantees. Inspect the lumber and consider the actual cutting layout before ordering a large quantity.
Board feet pricing
When lumber is sold by board foot, multiply the required board feet by the supplier's price per board foot.
This calculator lets each lumber size have its own price per board foot, which is useful when a project contains several species, grades or sizes.
Common lumber dimensions
| Nominal size | Typical use |
|---|---|
| 2 × 4 | Framing and general construction |
| 2 × 6 | Flooring, framing and heavier construction |
| 2 × 8 | Joists, beams and structural framing |
| 2 × 10 | Joists, rafters and larger framing |
| 2 × 12 | Large joists, beams and heavy framing |
Frequently asked questions
How many board feet are in a 2 × 4 × 8?
Using the nominal dimensions, the calculation is 2 × 4 × 8 ÷ 12, which equals 5.33 board feet.
How many board feet are in a 2 × 6 × 8?
Using nominal dimensions, 2 × 6 × 8 ÷ 12 equals 8 board feet.
Does board-foot calculation use actual or nominal dimensions?
Either measurement method works mathematically, but the dimensions should match the method used for pricing or ordering. Actual dimensions are preferred when the measured finished size is known.
How do I calculate board feet for multiple boards?
Calculate the board feet for one board and multiply the result by the quantity. For mixed sizes, calculate each size separately and add the results.
How much waste should I add to a lumber estimate?
A 10% allowance is a useful starting point for many estimates, but the right percentage depends on the cutting plan, lumber quality and project complexity.
Is a board foot the same as a cubic foot?
No. One board foot equals one-twelfth of a cubic foot. Twelve board feet equal one cubic foot.
