Feet to Linear Feet Calculator

Linear feet measure length only — the running length of a board, trim, fence or roll, regardless of width. Enter the area to cover and the width of the material to convert square feet to linear feet, see how many boards of a given length you need with a waste allowance, or convert linear feet of lumber to board feet.

What “linear feet” means

A linear foot is simply a foot of length, measured along the material, whatever its width or thickness. Lumber yards price boards, trim and mouldings by the linear foot; fencing, gutters, countertops and kitchen cabinets are often quoted by the linear foot; and fabric and carpet on rolls may be sold by the linear foot or yard. Square feet, by contrast, measure area. To convert between them, you need the width of the material.

Square feet to linear feet

Convert the covering width to feet: a deck board 5.5 inches wide with a ⅛-inch gap covers 5.625 inches, or 0.469 ft. Divide the area by that width: 240 ÷ 0.469 ≈ 512 linear feet. Add waste for cuts and defects — 10% is common for straight runs, 15% for diagonal patterns — giving about 563 linear feet, or 47 boards of 12 feet.

Nominal vs actual lumber sizes

Use the actual width for coverage calculations. For tongue-and-groove flooring or siding, use the exposed face width, not the full width including the tongue.

Board feet

Hardwood lumber is often sold by the board foot, a measure of volume equal to a board 1 inch thick, 12 inches wide and 1 foot long (144 cubic inches). Board feet = thickness (in) × width (in) × length (ft) ÷ 12. A 1 × 6 board 8 feet long is 1 × 6 × 8 ÷ 12 = 4 board feet. Rough hardwood is usually measured by nominal (rough) thickness in quarters of an inch — 4/4, 5/4, 8/4.

Trim and baseboard

For baseboard, crown moulding and other trim, measure the perimeter of the room and subtract door openings for baseboard (not for crown). A 14 × 12 ft room has a 52 ft perimeter; minus a 3 ft door opening leaves 49 ft. With 10% waste for mitre cuts, buy about 54 linear feet — for example five 12-ft lengths. Buying longer pieces reduces joints on long walls.

Waste allowance guide

Worked example: fence boards

A 60-foot fence run 6 feet high uses 5½-inch-wide pickets with ½-inch gaps. Treat the fence face as an area: 60 × 6 = 360 sq ft, but pickets run vertically, so count them instead: the fence length in inches (720) divided by the picket spacing (6 inches) gives 120 pickets of 6 feet — 720 linear feet. Adding 5% gives 126 pickets. The calculator’s area mode gives the same total when you enter 360 sq ft, width 5.5 in and gap 0.5 in.

Flooring and cladding

Hardwood flooring is usually sold by the square foot, but some suppliers price solid boards by the linear foot. Use the covering (face) width without the tongue: a 3¼-inch strip floor covers about 0.27 ft per linear foot, so 200 square feet needs about 740 linear feet before waste. Wall cladding such as shiplap works the same way with its exposed face width. Measure the room at the widest points, subtract large obstructions such as fireplaces, and add waste for cuts around doors and edges.

Fabric and rolls

Fabric, vinyl, landscape fabric and carpet on rolls are often sold by the linear foot or yard at a fixed roll width. To cover an area, divide the area by the roll width (in feet) to get linear feet, then round up to whole feet or yards. Allow extra for pattern matching and seams, and check whether the width quoted is the full width or the usable width after selvedges.

Pricing by the linear foot

When comparing prices, make sure you compare the same thing: a price per linear foot for a 1 × 6 is not comparable to one for a 1 × 8, and a price per piece must be divided by its length. Enter the price per linear foot to see the total cost for the boards you need.

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