Plan a shiplap accent wall, bathroom or ceiling in seconds. Enter the wall size and openings, choose the board width (its exposed face) and length, and get the number of boards, linear feet, rows and an approximate nail count.
Last updated:
Wall
ft
ft
sq ft
Windows, doors, fireplace. A 3 × 4 ft window = 12 sq ft.
Boards
Exposure = visible face per row (board width minus the overlap, plus any gap).
in
%
10% for plain walls, 15% with many openings or angled cuts.
$
Optional.
Enter your values to see the result.
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How to use the Shiplap Calculator
Measure the wall width and height in feet and enter how many walls of that size you are covering.
Subtract openings such as windows, doors or a fireplace in square feet.
Pick the board: its exposure is the visible face per row. Choose Custom and measure one board if yours differs.
Choose the board length, waste allowance, stud spacing and nails per stud.
Read the results: boards to buy, linear feet, rows and nails, then compare other widths in the table.
Shiplap formula
Linear feet = (wall area − openings) × 12 ÷ exposure (in), then boards = linear feet × (1 + waste) ÷ board length, rounded up.
Example: two 10 × 8 ft walls with a 15 sq ft window, 1×8 shiplap (6 7/8 in exposure), 12 ft boards and 10% waste:
area = 160 − 15 = 145 sq ft; linear feet = 145 × 12 ÷ 6.875 = 253.1 ft; with waste 278.4 ft; boards = 278.4 ÷ 12 = 23.2 → 24 boards.
Rows per wall = 96 in ÷ 6.875 = 13.96, so 14 rows with a narrow rip on the last one.
Nails ≈ rows × studs crossed × nails per stud. Studs crossed = wall width in inches ÷ stud spacing + 1.
Shiplap board sizes and coverage
Board
Actual width
Typical exposure
Linear ft per 100 sq ft
8 ft board covers
1×4
3 1/2 in
≈ 3 1/8 in
384
2.08 sq ft
1×6
5 1/2 in
≈ 5 1/8 in
234
3.42 sq ft
1×8
7 1/4 in
≈ 6 7/8 in
175
4.58 sq ft
1×10
9 1/4 in
≈ 8 7/8 in
135
5.92 sq ft
1×12
11 1/4 in
≈ 10 7/8 in
110
7.25 sq ft
Exposure varies by mill and profile (nickel gap, true shiplap, tongue and groove), so measure one board from its top edge to the top of its lip and use the custom option for the most accurate count.
Let wood boards acclimate in the room for a few days before installing, start at the bottom with a level first row, and stagger end joints over studs.
Frequently asked questions
How do I calculate how much shiplap I need?
Multiply wall width by height and subtract openings to get the area. Convert it to linear feet with area × 12 ÷ exposure width in inches, add 10-15% waste, then divide by the board length and round up. A 12 × 8 ft wall with 1×6 shiplap (5 1/8 in exposure) needs 96 × 12 ÷ 5.125 = 225 linear ft, 247 ft with 10% waste, or 31 boards of 8 ft.
What is shiplap exposure width?
It is the visible face each board adds to the wall after the rabbeted lip overlaps the board below. A 1×6 shiplap board is about 5 1/2 in wide but covers roughly 5 1/8 in. Using the full width instead would undercount the boards.
How many square feet does a shiplap board cover?
Board length × exposure ÷ 12. An 8 ft 1×6 shiplap board with a 5 1/8 in exposure covers 8 × 5.125 ÷ 12 = 3.42 sq ft. A 16 ft 1×8 at 6 7/8 in covers about 9.2 sq ft.
How much waste should I add for shiplap?
Add about 10% for a plain wall and 15% when there are several windows, outlets, angled ceilings or you want to stagger joints with no repeating pattern. Knots and damaged ends also use up extra boards.
How many nails do I need for shiplap?
Nail each row into every stud. Face nailing uses 2 nails per stud, blind nailing through the lip uses 1. A 12 ft wall with studs 16 in apart has 10 studs, so 19 rows × 10 studs × 2 = 380 nails. 18-gauge brads about 2 in long or 6d-8d finish nails are common.
Can I use plywood strips instead of shiplap?
Yes. Ripping 4×8 sheets of 1/4 in or 1/2 in plywood into 6 in strips and spacing them with a nickel or 1/8 in spacer is a cheap way to get the look. Use the plywood strip preset, which counts a 6 1/8 in exposure.
Should shiplap go horizontal or vertical?
Horizontal boards make a room look wider and are easiest to nail into studs. Vertical boards make ceilings look taller but need horizontal blocking or a plywood backer to nail into. The area and linear feet stay the same either way.
Are all the tools on FreeToolCabin tested for quality and accuracy?
Yes! Every tool on our site undergoes automated Q/A testing in real browser environments to ensure high precision, correct output, and zero errors. If you happen to spot a bug or have a suggestion, please contact us at [email protected] and our team will review it right away.