Is a board foot the same as a linear foot?

No. A linear foot measures length only. A board foot measures volume, so a 12 inch wide 4/4 board has one board foot per linear foot while a 6 inch wide board has half.

Do I use rough or surfaced thickness in the formula?

Rough nominal thickness. A surfaced 4/4 board measuring 13/16 in is still sold and calculated as 1 inch, because you paid for the material removed in milling.

How do I convert board feet to cubic metres?

One board foot is 0.00236 cubic metres, so divide board feet by 424 to get cubic metres. Export lumber is usually quoted in cubic metres.

Lumber Board Feet

Calculate board feet for lumber orders

Thickness (in)

Width (in)

Length (ft)

Quantity

Board Feet

40.00 BF

4.00 BF per board × 10 boards

Quick Facts

•1 board foot = 144 cubic inches
•Formula: (T × W × L) ÷ 12
•A standard 2×4×8 = 5.33 board feet

Board Feet Explained

A board foot is a volume measurement for lumber: 1 foot long × 1 foot wide × 1 inch thick (144 cubic inches). The formula is: (Thickness × Width × Length) ÷ 12, where thickness and width are in inches and length is in feet. Hardwood lumber is typically priced per board foot.

Understanding the lumber board feet

Hardwood is priced by the board foot, a volume unit equal to 144 cubic inches, which is a piece 1 inch thick by 12 inches wide by 12 inches long. It confuses people because the thickness used in the formula is nominal rough thickness, written in quarters, not the finished dimension you measure after surfacing.

Worked examples

Board feet in a 4/4 walnut board, 7 in wide by 96 in long

1Formula: thickness in inches × width in inches × length in inches ÷ 144.
24/4 means 1 inch nominal thickness.
31 × 7 × 96 = 672 cubic inches.
4672 ÷ 144 = 4.67 board feet.

4.67 board feet. At 12 per board foot the board costs about 56.

Costing a table top in 8/4 maple

1Top needs 5 boards at 8/4 thickness, 6 in wide, 72 in long.
2Per board: 2 × 6 × 72 ÷ 144 = 6 board feet.
3Five boards: 30 board feet.
4Add 20 percent for jointing and defects: 36 board feet.

Order 36 board feet. At 9 per board foot that is 324 in material.

Nominal thickness in quarters

Quarter	Rough thickness	Typical surfaced (S2S)
4/4	1 in	13/16 in
5/4	1.25 in	1 1/16 in
6/4	1.5 in	1 5/16 in
8/4	2 in	1 3/4 in
10/4	2.5 in	2 1/4 in
12/4	3 in	2 3/4 in

Board feet per linear foot

Width	4/4	5/4	8/4
4 in	0.33	0.42	0.67
6 in	0.50	0.63	1.00
8 in	0.67	0.83	1.33
10 in	0.83	1.04	1.67
12 in	1.00	1.25	2.00

Practical tips

•Buy 20 to 30 percent more than the finished cut list. Rough lumber has checks, wane and cup that get cut away.
•Softwood dimension lumber like a 2x4 is sold by the piece, not the board foot, and its actual size is 1.5 by 3.5 inches.
•Mills round board widths down to the nearest inch on rough stock, so measure the narrow end when checking a tally.

Frequently asked questions

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This calculator is for educational and reference purposes only. Always verify critical calculations independently.