Board Foot Calculator

Calculate board feet for rough-sawn or dimensional lumber from thickness, width, length, and piece count. Add waste and an optional price per board foot.

Board thicknessin Enter a thickness greater than zero

Board widthin Enter a width greater than zero

Length per pieceft Enter a length greater than zero

Number of piecespieces Enter a whole number from 1 to 100,000

Waste allowance% Applied to total board-foot volume. Enter a percentage from 0 to 100

Price per board footUSD Optional; leave at zero when cost is not needed. Enter a price of zero or more

Calculation Results

Board feet including waste

—board ft

Use dimensions that match the supplier quote or the actual-volume question you are answering.

How to calculate board feet

Choose nominal or actual dimensions

Use nominal thickness and width when the lumber is quoted that way. Use measured actual dimensions when the goal is actual wood volume.

Enter one board size

Enter thickness and width in inches and length in feet. The standard formula requires this combination of units.

Enter the piece count

Quantity repeats the same board. Calculate different board sizes separately and add their board-foot totals.

Apply waste and price

Waste increases the planning volume. The optional price multiplies the adjusted board feet, not the piece count.

Board-foot volume formula

One board foot is a volume of 144 cubic inches: a board 1 inch thick, 12 inches wide, and 1 foot long. It is a volume measure, not a linear-foot measure.

Board feet per piece = Thickness (in) × Width (in) × Length (ft) ÷ 12

Base board feet = Board feet per piece × Quantity

Adjusted board feet = Base board feet × (1 + Waste ÷ 100)

Estimated cost = Adjusted board feet × Price per board foot

Nominal trade sizes can differ from dressed dimensions. This calculator does not silently convert one to the other because supplier pricing practices and the user’s purpose determine which dimensions are appropriate.

Common board-foot examples

The values use the entered dimensions and do not add waste.

Board dimensions	Length	Board feet per piece	Cubic feet
1 × 6 in	8 ft	4 bd ft	0.333 ft³
1 × 12 in	8 ft	8 bd ft	0.667 ft³
2 × 6 in	8 ft	8 bd ft	0.667 ft³
2 × 12 in	10 ft	20 bd ft	1.667 ft³

Methodology, assumptions and sources

The calculation uses the standard surfaced-lumber board-foot equation: thickness in inches multiplied by width in inches and length in feet, divided by 12. Waste is applied only after all identical pieces are totaled.

This calculator measures sawn-board volume. It does not use log-scaling rules such as Doyle, Scribner, or International 1/4-inch log rules.

Sources:

USDA Forest Service — Timber Products: Output and Use Factors — board-foot units and forest-products measurement context.
NIST Handbook 44, Appendix C (2026) — customary units and volume relationships.

Last reviewed: August 2026. These organizations do not endorse Efficienco.

Frequently asked questions

What is one board foot?

One board foot is 144 cubic inches of lumber volume, equivalent to 1 inch by 12 inches by 1 foot.

Should I use nominal or actual lumber dimensions?

Use the dimensions on which the supplier bases the quote for a pricing estimate. Use actual measured dimensions when you need actual wood volume.

How many board feet are in one cubic foot?

One cubic foot contains 12 board feet of volume because 1,728 cubic inches divided by 144 cubic inches equals 12.

Does the waste allowance choose extra board lengths?

No. It increases total board-foot volume. Purchasing still has to account for available lengths, grade, defects, cut layout, and required continuous pieces.