Shiplap calculator: how much shiplap do I need?
20 boards
of 12 ft · 20 rows at 5 in exposed (19.2 before rounding up) · 240 linear ft · for a 12 × 8 ft wall
Run your own numbers
Enter it the way you measured it: 4.5, 4 1/2,
3/8 or 10' 6".
20 boards
of 12 ft · 20 rows at 5 in exposed (19.2 before rounding up) · 240 linear ft
A 12 by 8 ft wall takes 20 boards of 12 ft shiplap at a 5 inch exposed face: 96 inches of height make 19.2 rows, rounded up to 20, and each row is one 12 ft board, 240 linear feet in all.
A worked example
A 15.5 by 9 ft accent wall in boards that show 7 1/8 inches, bought in 16 ft lengths, with a 10% waste allowance needs 18 boards. 108 inches of height at 7 1/8 inches is 15.16 rows, so 16; 16 rows of 15.5 feet are 248 linear feet, 272.8 with the allowance, which is 17.05 boards of 16 ft, so 18.
How do you figure how much shiplap you need?
Count rows, not square feet. Divide the wall height in inches by the exposed face of one board and round up, then multiply by the wall length for linear feet. The exposed face is narrower than the board, because its lap hides under the next one: measure one installed board, or a test piece against another.
How many linear feet of shiplap per square foot?
12 divided by the exposed face in inches: 2.4 linear feet per square foot at 5 inches, 2 at 6 inches and 1.71 at 7 inches. A price per square foot and a price per linear foot for the same board only compare once you know its exposure.
What else it is called
Shiplap is also sold as nickel gap boards, and searched as a shiplap calculator, shiplap coverage calculator or shiplap wall calculator. Some packages print a coverage width: that is the exposed face this page asks for, not the full width of the board.
Linear feet by wall and exposure
| Wall | Linear ft at 5 in exposed | Linear ft at 6 in exposed | Linear ft at 7 in exposed |
|---|---|---|---|
| 8 × 8 ft | 160 | 128 | 112 |
| 10 × 8 ft | 200 | 160 | 140 |
| 12 × 8 ft | 240 | 192 | 168 |
| 14 × 8 ft | 280 | 224 | 196 |
| 12 × 9 ft | 264 | 216 | 192 |
| 16 × 9 ft | 352 | 288 | 256 |
| 20 × 10 ft | 480 | 400 | 360 |
Rows are the wall height in inches ÷ the exposed face, rounded up; linear feet are rows × wall length. Divide by the length of your boards and add your waste allowance; the calculator does both.
Where the numbers come from
- A row of shiplap covers its exposed face, the part left showing once its lap hides under the next board. Rows = wall height in inches ÷ exposed face, rounded up, because the last row is ripped to fit and still takes a whole board; linear feet = rows × wall length; boards = linear feet × (1 + waste) ÷ board length, rounded up.
- The exposed face and the board length are the ones you read off your own boards, so none of the figures is ours to source, and no width is assumed: the lap differs from one maker and profile to the next.
This counts a solid wall. Take window and door widths off the wall length, or cover the scraps around them with the waste allowance; outside corners, trim and the ripped last row are not counted as separate pieces.
By Javier Miralles · Last updated . How this site is made.
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