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Shiplap Calculator

Construction

Calculate how many linear feet of shiplap boards you need for a wall, accounting for board overlap and wastage. Get an accurate material estimate fast.

55,000
312
0.251.5
030

Shiplap Needed

528
Wall Area
200

This calculator computes your Shiplap Needed, Wall Area from the values you enter.

Inputs
Wall AreaBoard WidthBoard OverlapWastage
Outputs
Shiplap NeededWall Area

What is a Shiplap?

A Shiplap Calculator estimates the total linear footage of shiplap boards needed to cover a wall, accounting for the overlapping joint between boards that reduces each board's effective coverage width. Because shiplap boards overlap slightly at their rabbeted edges, simply dividing wall area by the board's full physical width overestimates coverage and leads to buying too little material.

This calculator factors in that overlap automatically, giving you an accurate linear footage figure to order. If you're planning a broader interior finish project, the Drywall Calculator and Board and Batten Calculator cover related wall-covering material estimates.

How to use this Shiplap calculator

  1. Enter your Wall Area in square feet.
  2. Enter the Board Width for your chosen shiplap product in inches.
  3. Enter the Board Overlap amount — check your specific product's rabbet depth, or use the 0.5 inch default for standard profiles.
  4. Adjust the Wastage percentage based on your wall's complexity.
  5. Review the Shiplap Needed result in linear feet to place your material order.

Formula & Methodology

The calculator accounts for the overlap when determining effective board coverage:

Effective Width = Board Width − Overlap

Coverage per Linear Foot = Effective Width ÷ 12

Linear Feet Needed = ⌈(Wall Area × (1 + Wastage%)) ÷ Coverage per Linear Foot⌉

Worked example: For a 200 sq ft wall using 5.5 in boards with a 0.5 in overlap and 10% wastage:

Effective Width = 5.5 − 0.5 = 5 in

Coverage per Linear Foot = 5 ÷ 12 ≈ 0.417 sq ft

Adjusted Area = 200 × 1.10 = 220 sq ft

Linear Feet Needed = ⌈220 ÷ 0.417⌉ ≈ 528 linear ft

Frequently Asked Questions

The amount of shiplap needed depends on your wall's total area divided by the effective coverage width of each board — which is slightly less than the board's full width due to the overlapping shiplap joint — plus a wastage allowance for cuts. This calculator handles that calculation for you.
Shiplap boards have a rabbeted edge that overlaps the adjacent board, which means each board's effective coverage width is less than its full physical width. Ignoring this overlap when estimating material leads to buying too little board, since the overlapping portion doesn't add new wall coverage.
Overlap typically ranges from 0.25 to 0.75 inches depending on the specific shiplap profile and manufacturer, with 0.5 inches being a common default for standard nominal 1×6 or 1×8 shiplap boards.
Total linear footage needed equals your wall area divided by the effective coverage per linear foot of board (effective width in inches divided by 12), which the calculator computes automatically once you enter your wall area and board specifications.
A simple rectangular accent wall typically needs the standard 10% wastage allowance, while rooms with more corners, outlets, or window trim to cut around may benefit from a higher wastage percentage to avoid running short.
Yes, the linear footage calculation is the same regardless of installation orientation — the total board length needed depends on wall area and effective board coverage width, not on whether boards run horizontally or vertically.
Shiplap uses horizontal or vertical overlapping boards for a layered look, while board and batten uses vertical boards with narrow strips (battens) covering the seams between them — see the [Board and Batten Calculator](/board-and-batten-calculator/) for that style's material estimate.
Common shiplap board thickness is around 0.5 to 0.75 inches (nominal 1-inch lumber), which doesn't affect the linear footage calculation but is worth confirming with your supplier since it affects overall material weight and installation method.
Shiplap can typically be installed directly over drywall with proper fasteners into studs, or over furring strips for an added air gap — this calculator focuses on the shiplap board quantity itself, not the substrate preparation.
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