How do I convert linear feet to board feet?

Multiply the thickness in inches by the width in inches by the length in feet, and divide by 12. Twenty 8 ft pieces of 1×6 are 160 linear feet; on the nominal 1 × 6 that is 1 × 6 × 160 ÷ 12 = 80 board feet. On the actual 3/4 × 5 1/2 in it is 55 — lumber yards usually bill the nominal figure.

How many linear feet do I need to cover a square footage?

Divide the area by the exposed width of one board in feet. 200 sq ft of siding or paneling with 5 1/2 in showing is 200 ÷ (5.5 ÷ 12) = 436 linear feet, which is 55 pieces at 8 ft. Use the face you see after the overlap or tongue, not the full board width.

What is the difference between linear feet and square feet?

Linear feet is length only — how far the boards would reach laid end to end. Square feet is an area, and you only get it from linear feet once you know how wide each board covers. The same 100 linear feet covers 45.8 sq ft at 5 1/2 in and 29.2 sq ft at 3 1/2 in.

How do I compare a price per linear foot with a price per metre?

A metre is 3.281 feet, so a price per metre is the price per foot times 3.281. $2.10 a linear foot is $6.89 a metre. Switch the calculator to metric and a typed price converts the same way.

Linear feet calculator

I know

Pieces

pcs

Length of each piece

Thickness

Width

Actual size (a 1×6 is 3/4 × 5 1/2). Type 1 × 6 to match a yard's nominal board feet.

Exposure (face showing)

Blank uses the full width. Type the face left after overlap or tongue.

Price (optional)

per ft

Leave blank to skip the cost line.

— linear ft

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The calculator converts between length, volume and area for one board size. It does not add waste for cuts, end joints or defects, and it cannot know whether your supplier bills board feet on the nominal or the actual size — ask, and type the size they use.

Pick what you know — a count of pieces, a board-foot figure, or an area to cover — and type the board's thickness, width and the length you buy. You get the total linear feet (or metres), the board feet and cubic metres, the square footage it covers at your exposure, the pieces to buy and, with a price, the cost.

Worked example

Imperial. Twenty 8 ft pieces of 1×6 (actual 3/4 × 5 1/2 in) are 160 linear feet. Board feet on the actual size: 0.75 × 5.5 × 160 ÷ 12 = 55 bd ft; on the nominal 1 × 6 it is 80. Laid at the full 5 1/2 in they cover 160 × 5.5 ÷ 12 = 73.3 ft². At $2.10 a linear foot the lot is $336.

Metric. Twenty 2.4 m pieces of 19 × 140 mm are 48 m. Volume: 0.019 × 0.14 × 48 = 0.128 m³. They cover 48 × 0.14 = 6.72 m². At $6.90 a metre the lot is $331.20.

On the job

Ask how the yard counts. Hardwood is sold by the board foot on rough thickness; construction lumber and trim by the piece or the linear foot; the invoice for a big order may show nominal board feet. Match the size you type to the way the price is quoted or the comparison is meaningless.

Coverage uses the face, not the board. 1×6 tongue-and-groove shows about 5 1/8 in, not 5 1/2. Across 200 ft² that is 468 linear feet instead of 436 — four extra 8 ft boards the order is short if you use the full width.

Add waste after the conversion. This is the exact length. Trim with many short runs wastes 10–15% in offcuts; paneling or siding with end joints, about 10%. Add it to the pieces you buy.

What went wrong?

Quick referencefor boards

Board feet: thickness (in) × width (in) × length (ft) ÷ 12
Cubic metres: thickness (m) × width (m) × length (m) · 1 bd ft = 0.00236 m³ · 1 m³ = 423.8 bd ft
Area covered: linear ft × exposure (in) ÷ 12 = ft² · metres × exposure (m) = m²
Linear ft per 100 ft²: 3 1/2 in face 343 · 5 1/2 in 218 · 7 1/4 in 166
Price: per metre = per foot × 3.281 · per foot = per metre × 0.3048

The formula

linear ft = pieces × length · bd ft = T × W × linear ft ÷ 12 · ft² = linear ft × exposure ÷ 12

T and W are the thickness and width in inches, exposure in inches too. Working backwards, linear feet = board feet × 12 ÷ (T × W), or area × 12 ÷ exposure, and the pieces to buy are the linear feet over one length, rounded up.

Questions

How do I convert linear feet to board feet?: Multiply the thickness in inches by the width in inches by the length in feet, and divide by 12. Twenty 8 ft pieces of 1×6 are 160 linear feet; on the nominal 1 × 6 that is 1 × 6 × 160 ÷ 12 = 80 board feet. On the actual 3/4 × 5 1/2 in it is 55 — lumber yards usually bill the nominal figure.
How many linear feet do I need to cover a square footage?: Divide the area by the exposed width of one board in feet. 200 sq ft of siding or paneling with 5 1/2 in showing is 200 ÷ (5.5 ÷ 12) = 436 linear feet, which is 55 pieces at 8 ft. Use the face you see after the overlap or tongue, not the full board width.
What is the difference between linear feet and square feet?: Linear feet is length only — how far the boards would reach laid end to end. Square feet is an area, and you only get it from linear feet once you know how wide each board covers. The same 100 linear feet covers 45.8 sq ft at 5 1/2 in and 29.2 sq ft at 3 1/2 in.
How do I compare a price per linear foot with a price per metre?: A metre is 3.281 feet, so a price per metre is the price per foot times 3.281. $2.10 a linear foot is $6.89 a metre. Switch the calculator to metric and a typed price converts the same way.

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