Linear Feet to Board Feet

A run of lumber in; the board feet in it, and in every foot, out.

Counts board feet by PS 20's nominal sizes; your yard's prices win.

Units

Thickness: 2, 1 1/2 or 5/4

1 1/4" · 5/4 · 1.25 in · 0.1042 ft · 0.0318 m

Width

10" · 10 in · 0.8333 ft · 0.254 m

Length

8' · 96 in · 8 ft · 2.4384 m

Quantity

Add or subtract

41.67 board feet

Measure the boards by

Waste (%) ≈

Knots, checks and saw cuts: 10–15% is usual for surfaced stock; rough hardwood for furniture runs 25–30% (McIlvain). Added once, to what you buy.

Price per board foot ($)

Your yard's price; the answer says it in the other three units.

This page recalculates as you type. There is no Calculate button.

Answer

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In a linear foot, at nominal size

1.042 BF per linear foot

40 linear ft · 0.042 MBF · 45.83 board feet at nominal size with 10% waste

Board feet at nominal size, as lumber is billed 41.67 board feet

At the dressed size you take home (PS 20) 30.83 board feet

Linear feet 40 linear ft

Thousand board feet, at nominal size 0.042 MBF

With 10% waste, at nominal size, before the list rounds up 45.83 board feet

Breakdown

Boards	Measurements	Qty	Board feet	Share
Board 1	1 1/4" × 10" × 8'	Add ×5	41.67 board feet	100%

What to buy

Shopping list

5/4×10 × 8 ft 6 boards no price

Ticked items no price

Softwood is sold by the board, at the shortest length on the list that holds yours; hardwood by the board foot. Untick what you have.

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How this was worked out

Every number below is yours. Each constant links to the row where you can change it.

Board 1: board feet 1 1/4" × 10" × 96" ÷ 144 × 5 41.667 BF

Board 1: dressed size (PS 20) 1 1/4" − 1/4" = 1" · 10" − 3/4" = 9 1/4" 1" × 9 1/4"

Change:Dressed, boards 1 to 1½ in Dressed, 8 in and wider

Board 1: board feet at that size 1" × 9 1/4" × 96" ÷ 144 × 5 30.833 BF

Board 1: a linear foot 1 1/4" × 10" ÷ 12 1.042 BF/ft

Thousand board feet 41.667 ÷ 1,000 0.0417 MBF

Waste 41.667 BF × (1 + 10%) 45.833 BF

Assumptions

Every one of these is editable. Change one and the answer changes with it.

Assumption	Value	Confidence
Dressed, boards under 1 inNIST PS 20-20, Table 3 (p. 16): a board ¾ in nominal is dressed dry to ⅝ in. This is the ¾ in board's figure, used for every board under 1 in; PS 20 dresses the ⅜, ½ and ⅝ in boards 1/16 in under, which this does not model.	in	From a data sheet or an agency document
Dressed, boards 1 to 1½ inNIST PS 20-20, Table 3 (p. 16): a board from 1 in and under 2 in nominal is dressed dry ¼ in under it - 1 to ¾, 1¼ to 1, 1½ to 1¼.	in	From a data sheet or an agency document
Dressed, 2 in up to 8 inNIST PS 20-20, Table 3: from 2 in nominal and under 8 in wide, lumber is dressed dry ½ in under it - 2 to 1½, 4 to 3½, 6 to 5½.	in	From a data sheet or an agency document
Dressed, 8 in and widerNIST PS 20-20, Table 3: 8 in nominal and wider is dressed dry ¾ in under it - 8 to 7¼, 10 to 9¼, 12 to 11¼.	in	From a data sheet or an agency document
Dressed green, timbersNIST PS 20-20, Table 3: timbers, 5 in nominal and thicker, are dressed green ½ in under nominal on both faces - 6×6 to 5½ × 5½, 8×8 to 7½ × 7½. Timbers are sold green; dried, 7 in and up loses more.	in	From a data sheet or an agency document
Boards' ¼ in fromNIST PS 20-20, Table 3: from 1 in nominal a board is dressed ¼ in under; thinner boards less.	in	From a data sheet or an agency document
Dimension lumber fromNIST PS 20-20: dimension lumber starts at 2 in nominal thickness; boards are thinner.	in	From a data sheet or an agency document
The wide allowance fromNIST PS 20-20, Table 3: the dressed allowance goes from ½ in to ¾ in at 8 in nominal width.	in	From a data sheet or an agency document
Timbers fromNIST PS 20-20: timbers are lumber 5 in nominal and thicker in the least dimension.	in	From a data sheet or an agency document

Linear feet to board feet

Multiply the linear feet by the thickness and the width in inches, and divide by 12. A 2×6 is 2 × 6 ÷ 12 = 1 board foot (BF) in every linear foot, so 100 linear feet of 2×6 is 100 board feet. A 1×6 is half a board foot a foot; a 2×12, two.

Lumber	Board feet a linear foot
1×4	0.333
1×6	0.5
1×8	0.667
1×12	1
2×4	0.667
2×6	1
2×8	1.333
2×10	1.667
2×12	2
4×4	1.333
6×6	3

Type the whole run into the length box — 100 for 100 ft — or one board's length and the number of boards beside it. Both come to the same board feet.

These are nominal sizes, the ones a yard bills by. The 2×6 is really 1½ in by 5½ in, so the same 100 linear feet hold 68.75 board feet of wood. The answer prints both.

Buying a run

No yard sells a 100 ft board. The list buys the run in the longest boards it holds, 20 ft: five of them, and six once 10% for cuts and defects is on. Shorter pieces add joints; the list does not plan the cuts, it counts the boards.

A price per linear foot works the same way backwards: choose "per linear foot" under "The price is", and the answer says what that is per board foot and per board.