Shiplap Calculator: Boards, Square Feet and Linear Feet

Enter the size of the wall, the openings, the full width of a board and the lap. The board shows its width less the lap, and you get the area, the linear feet, the number of boards with an allowance for waste, and the courses up the wall.

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Results

Example job shown. Change the numbers to match yours.

Width each board showsThe board width less the lap: 5.000 in
Wall area to coverLess the openings: 76.0 sq ft
Linear feet of boardArea divided by the width shown, in feet: 182.4 ft

Boards to buy

26 boards

Of 8 ft, with 10% extra

Courses up the wallRows of board from the floor to the ceiling, the last one cut: 20 courses
Square feet covered by one board: 3.33 sq ft

Shiplap boards overlap along the edge, so each board shows less than its full width: a board 5⅜ in wide with a 3/8 in lap shows 5 in. The linear feet are the area divided by the width shown, in feet, and the boards are that length with the extra for waste divided by the length of a board. Pick the board length that suits the wall, so joints land on studs and the scraps are short. Check the width of the board you buy, because shiplap profiles differ, and for a nickel gap or a wider reveal, subtract the gap from the width as well as the lap. Allow more for a diagonal or a herringbone pattern.

Before you buy: round up to whole packs, check the size printed on the label, and add a little spare. Your supplier has the final say.

How this calculator works

Worked example: a board 5⅜ in wide with a 3/8 in lap shows 5 in. A wall 12 × 8 ft is 96 sq ft, and less 20 sq ft of openings it is 76 sq ft. That takes 182.4 linear feet of board, and with 10% extra 26 boards of 8 ft. There are 20 courses from the floor to the ceiling, and one board covers 3.33 sq ft. With no openings it is 32 boards, with boards of 10 ft 21, with 7⅜ in wide boards 18, and with 15% extra 27.

Shiplap for common walls (8 ft high, 5 in shown, 8 ft boards, 10% extra, no openings)

Square feet, linear feet and boards.

Wall length	Square feet	Linear feet	Boards of 8 ft
8 ft	64	154	22
10 ft	80	192	27
12 ft	96	230	32
14 ft	112	269	37
16 ft	128	307	43
20 ft	160	384	53

Tips before you buy

Check the width of the board you buy: the width shown depends on its profile, and may not be 5 in.
Start from the bottom and keep each course level, or from the top if the ceiling is flatter than the floor.
Leave a gap of about 1/8 in between boards to allow for the swelling of the wood in the damp.
Fix into the studs, and stagger the end joints of the boards in nearby courses.
Prime and paint the boards on all sides before you hang them, so a bare edge does not show if they shrink.

Tools & materials for this project

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Shiplap boards 1×6 Finish nailer Stud finder Laser level Wood filler

Frequently asked questions

How much shiplap do I need?

The wall area divided by the width each board shows, in feet, plus waste: for 76 sq ft that is 182.4 linear feet, or 26 boards of 8 ft with 10% extra.

How wide is a shiplap board when it is on the wall?

It shows its full width less the lap: a 1×6 board about 5⅜ in wide with a 3/8 in lap shows 5 in.

How much extra shiplap should I buy?

About 10% for a straight pattern and 15% for a diagonal or a herringbone, because of the cuts at the ends and the openings.

How many square feet does one board cover?

A board of 8 ft that shows 5 in covers 3.33 sq ft.

Does shiplap need a gap between boards?

Many installers leave about 1/8 in (a nickel gap) so the boards can move. Subtract the gap from the width shown if you want it counted.

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Related calculators & guides

Estimates only. Results assume standard materials and simple shapes. Supplier products vary, and the final call on quantity, structure and safety is yours. Check your local code and your supplier's guidance before ordering.

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