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How to calculate board feet

A board foot is 144 cubic inches of lumber: 12" × 12" × 1". Multiply thickness × width in inches by the length in feet, then divide by 12.

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Page 1 of the printable board feet chart: Board feet for common lumber sizes and lengths, and per linear foot by thickness and width. — The printable chart. US Letter, 1 page.

Board feet by nominal size and length

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Nominal size	Per foot	8 ft	10 ft	12 ft	14 ft	16 ft
1x4	0.33	2.67	3.33	4	4.67	5.33
1x6	0.5	4	5	6	7	8
1x8	0.67	5.33	6.67	8	9.33	10.67
1x10	0.83	6.67	8.33	10	11.67	13.33
1x12	1	8	10	12	14	16
2x4	0.67	5.33	6.67	8	9.33	10.67
2x6	1	8	10	12	14	16
2x8	1.33	10.67	13.33	16	18.67	21.33
2x10	1.67	13.33	16.67	20	23.33	26.67
2x12	2	16	20	24	28	32
4x4	1.33	10.67	13.33	16	18.67	21.33
4x6	2	16	20	24	28	32
6x6	3	24	30	36	42	48

By nominal size: a 2x4 counts as 2" × 4". To 2 decimal places.

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Board feet per linear foot by thickness and width

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Thickness	4" wide	6" wide	8" wide	10" wide	12" wide
1/2"	0.33	0.5	0.67	0.83	1
3/4"	0.33	0.5	0.67	0.83	1
4/4 (1")	0.33	0.5	0.67	0.83	1
5/4 (1-1/4")	0.42	0.63	0.83	1.04	1.25
6/4 (1-1/2")	0.5	0.75	1	1.25	1.5
8/4 (2")	0.67	1	1.33	1.67	2

Boards under 1" count as 1", so the 1/2" and 3/4" rows match 4/4. Some yards count the fraction: ask yours.

How many board feet are in a 2x4x10?

6.67 board feet: 2 × 4 × 10 ÷ 12. A 2x4x8 is 5.33 board feet, a 2x6x8 is 8, and a 4x4x8 is 10.67.

If the length is in inches too, divide by 144 instead.

Do I use the real size or the nominal size?

The nominal size: a 2x4 counts as 2" × 4", though a dry one is really 1-1/2" × 3-1/2". So a 2x4x8 is 5.33 board feet on the bill, or 3.5 board feet of actual volume.

What do 4/4 and 5/4 mean?

Hardwood is sold in quarters of an inch: 4/4 is 1", 5/4 is 1-1/4", 6/4 is 1-1/2" and 8/4 is 2". A 5/4 board 6" wide holds 0.63 board feet per foot.

How are board feet different from square and linear feet?

A board foot is volume, a square foot is area, a linear foot is length. A 2x6 holds exactly 1 board foot per linear foot, so a 2x6 that is 14' long is 14 board feet.