What is the difference between a board foot and a lineal foot?

A lineal foot measures length only. A board foot measures volume, so it accounts for thickness and width as well — two boards of the same length can differ greatly in board footage.

Should I use nominal or actual dimensions?

Use nominal rough dimensions. A 2x6 that measures 1.5 x 5.5 inches after surfacing is still bought and priced as a 2x6.

How many board feet are in a 2x4x8?

Two inches by four inches by eight feet divided by twelve gives 5.33 board feet.

Why is my hardwood invoice higher than this estimate?

Yards often charge a surfacing fee, a short-length premium, or round each board up to the next quarter board foot. Grading also affects price per board foot.

Does this work for metric lumber?

The board foot is an imperial measure. Convert millimetres to inches and metres to feet first using our conversion tools, then run the calculation.

Trade Calculators

Board Foot / Lumber Calculator

Board feet and lumber cost from thickness, width and length.

Inputs

Given

Thickness

Width

Length measured in

Length

Quantity

pcs

Price per board foot

Results

Computed

Total board feet

80.00

8.000 board feet per piece × 10 pieces

Board feet per piece8.000

Total lineal feet80.0 ft

Estimated material cost$360.00

Cost per piece$36.00

Board footage is calculated on nominal rough dimensions. Surfaced lumber (S4S) is thinner and narrower than nominal but is still sold at the rough measure.

80.00 bd ft · $360.00

FIG. 3 — BOARD FOOT = T × W × L ÷ 12

How this is calculated

A board foot is a volume measure: 144 cubic inches of lumber, equal to a piece one inch thick, twelve inches wide and one foot long. Because thickness and width are measured in inches while length is usually in feet, the standard formula divides by 12:

board feet = thickness(in) × width(in) × length(ft) ÷ 12

When every dimension is in inches, divide by 144 instead — that is what this tool does internally:

board feet = thickness(in) × width(in) × length(in) ÷ 144

Hardwood is graded in quarters of an inch: 4/4 is one inch, 5/4 is one and a quarter, 8/4 is two inches. Always use the rough nominal thickness in the calculation even if the board has already been surfaced, because that is how mills and yards price it.

Cost is simply total board feet multiplied by your price per board foot. Add a waste factor for defects, snipe and cutting — 15% is typical for rough lumber and 25% or more if you are working around knots and checks in character-grade stock.

Worked example

Pricing a hardwood order

You need 20 boards of 8/4 (2 in) white oak, 6 in wide, 8 ft long.
Board feet each = (2 × 6 × 8) ÷ 12 = 8 bf.
Order total = 20 × 8 = 160 bf.
At $9.50/bf the wood runs 160 × 9.50 = $1,520 before tax.
In Canada, add provincial sales tax — e.g. 13% HST in Ontario brings it to about $1,718.

Common mistakes

Using nominal dimensions
A '2×4' measures 1½ × 3½ in. Board-foot pricing uses actual thickness and width — using nominal sizes overstates volume by roughly 30% on common dimensions.
Mixing quarters with inches
Hardwood thickness is sold in quarters of an inch: 4/4 = 1 in, 8/4 = 2 in. Entering '8' instead of '2' for an 8/4 board quadruples the calculated volume.
Forgetting surfaced lumber loses thickness
S2S or S4S milling removes material: rough 4/4 stock typically finishes at 13/16 in. If you need a full finished inch, buy 5/4 rough stock.