Shiplap Calculator
Shiplap boards and lineal feet for a wall area.
Result appears here
Fill in the fields and press Calculate.
Formula, calculation, assumptions and sources
Net area = wall width × height − openings
Lineal feet = net area ÷ board reveal (exposed face width)
Boards = lineal feet ÷ board length
Rows = wall height ÷ board reveal
Run the calculation to see each step with your own numbers.
A 16 ft × 8 ft wall, one 3×7 ft door (21 ft²), 5" reveal boards, 8 ft lengths, 10% waste.
Net area = 128 − 21 = 107 ft²
Lineal feet = 107 ÷ (5/12) = 257 ft → order 283 ft with 10%
Boards = 257 ÷ 8 = 33 → order 36
- Boards run horizontally. The 'reveal' is the exposed face width after the shiplap or nickel-gap joint — always less than the nominal width.
- Openings are deducted from the area but every course above and below an opening still needs a cut, so keep the waste allowance.
- Trim, inside/outside corners, fasteners and finish are separate.
- Why not just use the nominal board width?
- A 1x6 board is 5½" wide, but the shiplap rabbet and (for nickel-gap) the deliberate gap mean only about 5" actually shows. Using the nominal width would leave you short.
- What reveal should I enter?
- The visible height of one board after the next laps over it — about 5" for a nominal 1x6, 7" for a 1x8. For nickel-gap, the deliberate 1/8" gap is already part of the reveal on most milled profiles.
- Horizontal or vertical — does the count change?
- The board and lineal-foot total is the same either way. Vertical shiplap needs blocking between the studs and usually wastes a little more at the top and bottom, so nudge the allowance up.
Coverage method
Lineal feet = area ÷ exposed face width — standard board-coverage geometry, matches shiplap/paneling manufacturer coverage tables (reveal ≈ 5 in for 1x6, 7 in for 1x8).
Unit conversion
About the Shiplap Calculator
The Shiplap Calculator turns a wall area into shiplap boards and lineal feet, working from the board's exposed face width (the reveal) after the shiplap or nickel-gap joint — always less than the nominal size, so using the nominal width leaves you short. It also gives the number of courses up the wall. Trim, corners and fasteners are separate.
What you enter
- Wall width
- Wall height
- Openings to deduct
- Exposed face width per board (reveal) — The visible coverage of one board after the lap — a nominal 1x6 shiplap covers ≈ 5". A 1x8 covers ≈ 7".
- Board length — Stock length you'll buy — 8, 12 or 16 ft.
- Waste allowance — Default 10%. Adjust to your own allowance — the exact figure is always shown too.
What you get back
- Net wall area — the exact result of the calculation.
- Lineal feet of shiplap — shown as the exact figure and, separately, a recommended figure with your waste allowance added.
- Boards — shown as the exact figure and, separately, a recommended figure with your waste allowance added.
- Rows (courses) up the wall — the exact result of the calculation.
The formula, a worked example, the assumptions behind it and the sources are shown in full below the calculator.
Related calculators
- Wall Square Footage Calculator — Wall area for one or more walls, with openings deducted.
- Siding Calculator — Siding material and squares for the exterior walls of a building.
- Board Foot Calculator — Board feet for a piece or a list of lumber from its dimensions.
- Drywall Calculator — Drywall sheets, screws, mud and tape for a room.
Part of the Walls calculators.