Work out how many shiplap boards you need with our free calculator. Get board count, furring strips, trim lengths, and a full cost estimate in seconds.
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Shiplap projects live and die on board count. Order too few and you’re making a second trip to the lumber yard mid-install. Order too many and you’ve tied up money in boards you’ll return. This calculator takes the wall dimensions you already have and returns the numbers you actually need: rows of boards, boards per row, total board count with waste, furring strip length, fastener boxes, trim lengths, and a full cost estimate. It handles three wall input modes so you can work from a single wall, a room perimeter, or a direct area entry. Contractors use it for bids; homeowners use it to sanity-check material lists. Everything runs in your browser. No signup, no data leaves your device.
Choose your unit system. Pick imperial (inches, feet, square feet) or metric (millimeters, meters, square meters). Every input follows that choice.
Pick a wall input mode. Single Wall uses length and height. Perimeter uses room dimensions. Direct Area Entry takes a known square footage.
Enter wall dimensions and openings. Add the wall sizes, then subtract doors and windows by count, width, and height.
Set your board. Pick a preset (1×4 through 1×10, or nickel gap) or enter custom width, reveal, and stock length. Reveal drives board count, not nominal width.
Choose orientation and waste. Horizontal runs boards parallel to the floor; vertical stacks them floor to ceiling. Waste defaults to 10%.
Configure furring and fasteners. If you’re adding furring strips, set the on-center spacing. Then pick a fastener type and set fasteners per board and per box.
Add trim and finish. Toggle baseboard, crown, corner trim, and paint or stain. Enter trim piece length so the tool can estimate piece count.
Enter cost figures and read the summary. Add unit costs for materials and labor, then check the result panel for boards, lengths, boxes, and total cost.
Board count comes from two numbers: how many rows you need and how many boards fit in each row. Rows = ceiling of wall height divided by reveal width. Boards per row = ceiling of wall length divided by stock board length. Multiply those together and you have the net board count.
Formula: Rows = Ceiling(Wall Height ÷ Reveal Width)
Formula: Boards per Row = Ceiling(Wall Length ÷ Stock Board Length)
Formula: Total Boards (net) = Rows × Boards per Row
Formula: Total Boards (with waste) = Ceiling(Net Boards × (1 + Waste % ÷ 100))
Formula: Net Wall Area = Gross Wall Area − (Doors × Door Width × Door Height) − (Windows × Window Width × Window Height)
For vertical orientation, the axes swap: columns across the wall width replace rows, and boards per column come from dividing height by stock length. Horizontal is the standard install for most rooms, but vertical works well on accent walls and short runs.
Furring strip count depends on orientation. For horizontal boards, furring rows = ceiling of wall height divided by furring spacing, plus one extra strip. Multiply that by the wall length and any duplicate walls. Fastener count is straightforward: total boards with waste times fasteners per board, then rounded up to full boxes.
The cost side multiplies each material length by its per-foot price. Labor and additional costs get added on top. Cost per square foot divides the total by net wall area.
Here’s a 14-foot by 9-foot accent wall with a 3×7 door and a 4×5 window. Board preset is 1×6 with a 5.5-inch reveal. Stock length is 12 feet, horizontal, 10% waste. Furring at 16 inches on center.
Gross area: 14 × 9 = 126 ft².
Openings: Door is 3 × 7 = 21 ft². Window is 4 × 5 = 20 ft². Total openings = 41 ft². Net area = 126 − 41 = 85 ft².
Rows: Height 9 ft = 108 in. Reveal 5.5 in. 108 ÷ 5.5 = 19.64, rounded up to 20 rows.
Boards per row: Length 14 ft. Stock 12 ft. 14 ÷ 12 = 1.17, rounded up to 2 boards per row.
Net boards: 20 × 2 = 40 boards.
With waste: 40 × 1.10 = 44 boards.
Board length required: 44 × 12 = 528 linear feet.
Furring: 108 ÷ 16 = 6.75, rounded up plus one = 8 rows. 8 × 14 = 112 linear feet. Add roughly 10% for cuts: about 124 linear feet, or 11 pieces of 12-ft strip.
Fasteners: 44 boards × 6 fasteners = 264 pieces. One 1,000-count box covers it.
Cost check: At $1.85 per linear foot for shiplap: 528 × 1.85 = $976.80. Furring at $0.65 per foot: 124 × 0.65 = $80.60. Fasteners at $45 per box: $45. Trim, finish, and labor on top.
Interpretation: You need 44 boards, 11 furring strips, 1 box of fasteners, and about $1,100 in materials before trim and labor. The board count runs slightly high because the tool rounds up per row, but that keeps you from running short mid-install.
Multiply wall length by height, subtract openings, then divide height by reveal width for row count and length by stock board length for boards per row. Multiply those two. Add waste. For a 14×9 wall with 5.5-inch reveal and 12-ft stock, that’s 40 boards, or 44 with 10% waste.
1×6 is the standard. It’s widely stocked in 12-ft and 16-ft lengths and works on most 8-ft to 10-ft walls. 1×8 shows up on larger walls where fewer horizontal lines look better. Nickel-gap comes in 5/8×6 and 5/8×8.
The reveal is the visible face of each board after installation. A 1×6 board has a 6-inch nominal width but a 5.5-inch reveal once the overlap is accounted for. Board count uses the reveal width, not the nominal width.
10% is a safe default for a basic rectangular wall. Bump to 15% if the wall has outlets, switches, or a light fixture to work around. For stairwells and angled ceilings, 20% is safer. The calculator caps at 40%.
Yes. Switch orientation to Vertical and the tool flips the axes. Columns run across wall width, and boards per column come from dividing height by stock length. Board count changes because stock length efficiency changes.
The math works for any linear board layout, but exterior installs usually need different fasteners, sheathing, and moisture barriers. Use the calculator for material quantity only, and check local code for exterior shiplap requirements.
Not always. If the wall is flat and you’re nailing into studs, you can skip them. On uneven plaster, masonry, or any wall where you want a small air gap, furring strips are worth the extra material. The calculator toggles them on or off.
Increase your stock board length to reduce boards per row, or use a wider board to reduce row count. A 1×8 with a 7.25-inch reveal needs fewer rows than a 1×6 with a 5.5-inch reveal. Wider boards cost more per piece but cut install time.
It can. Toggle baseboard, crown, corner trim, and finish in the Trim & Finish section. The tool calculates each length and adds it to the cost total. Leave them off if you only need shiplap board count.
Nickel-gap has a small gap between boards when installed, usually 1/8 inch. The reveal is slightly narrower than a standard 1×6 because of the gap. Otherwise the install method and board count logic are the same.
It’s accurate to the rounding rules built into the tool: rows round up, boards per row round up, and waste rounds up. That means your count is slightly conservative, which protects you from mid-project shortages. Verify your wall measurements before ordering.
Yes. Set wall mode to Single Wall, enter length and height, and leave the number of identical walls at 1. That’s the most common use case for shiplap projects.
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