Linear Feet Calculator

Linear Feet formula

Linear feet (boards) = Area (sq ft) x 12 / board width (in)
Linear feet (perimeter) = 2 x (Length + Width)
With waste = Linear feet x (1 + waste %)
Pieces = With waste / stock length, rounded up

Worked example

A 320 sq ft deck surface with 5.5 in wide deck boards: 320 x 12 / 5.5 = 698.2 linear feet. Add 10% waste for 768 ft. At 16 ft stock, 768 / 16 = 48 boards. Check: 698.2 x 5.5 / 12 = 320 sq ft.

Baseboard for a 14 x 16 ft room: 2 x (14 + 16) = 60 linear feet. With 10% waste that is 66 ft, and at 12 ft stock 66 / 12 = 5.5, so buy 6 pieces. Subtract door openings only if you are confident of the cut list; most people leave them in as extra waste.

Quick reference

Square feet to linear feet

Boards, planks, decking and shiplap are sold by the linear foot, but you measure the area you need to cover in square feet. To convert, divide the area by the width of one board in feet, or equivalently multiply by 12 and divide by the width in inches. The wider the board, the fewer linear feet you need. Always use the actual face width, not the nominal size, and for tongue-and-groove use the exposed face after the joint is closed.

Once you have the linear feet, add waste and divide by the stock length you plan to buy. Pick a length that matches your runs: 12 ft boards on a 12 ft wall have no end cuts, while 8 ft boards on the same wall create a joint and a 4 ft leftover.

Measuring a perimeter

For baseboard, crown, chair rail, or a fence line, linear feet is the distance around the space: twice the length plus twice the width for a rectangle. For an L-shaped room, measure each wall segment and add them. Door openings can be subtracted, but leaving them in gives a built-in waste margin for the miters at corners.

Count corners too. Each outside corner on trim needs a miter, and each 12 ft stick can only cover so many walls without a seam, so a room with eight short walls needs more pieces than the raw footage suggests. Round up to whole pieces of stock and keep one spare.

Key facts

• A linear foot is simply 12 inches measured along a length; width and thickness do not change it.
• Nominal lumber is narrower than its name: a 1x4 is 3.5 in wide, a 1x6 is 5.5 in, a 1x8 is 7.25 in, and a 1x12 is 11.25 in.
• 100 sq ft of 1x6 boards is 218.2 linear feet, while 100 sq ft of 1x4 is 342.9 linear feet.
• Lumber yards and trim suppliers price by the linear foot, while flooring and sheet goods are priced by the square foot.
• Standard stock lengths are 8, 10, 12 and 16 ft; choosing a length that divides evenly into your runs cuts waste.

Frequently asked questions

Sources and references

• •Voluntary Product Standard PS 20-20, American Softwood Lumber Standard (NIST)
• •NIST Handbook 44, Appendix C, General Tables of Units of Measurement (NIST)
• •Nominal vs Actual Lumber Sizes (Southern Pine Inspection Bureau)