Free estimate — verify against local code before building
Shiplap Calculator
Use installed board coverage to plan shiplap stock, fasteners, waste, and optional cost.
What this calculator includes
Turn measured wall surfaces into a shiplap purchase list using the installed face coverage rather than the board's nominal width. Enter wall size, repeated walls, openings, orientation, stock length, support spacing, fastener packaging, waste, and optional prices to see both the net takeoff and the whole boards and fastener packs to buy.
How to use this shiplap calculator
- 01
Measure the finish surfaces
Enter wall length, height, identical-wall count, and the area of doors, windows, or other surfaces that will not receive shiplap.
- 02
Use installed face coverage
Enter the exposed face after the lap or tongue engages, not the nominal board width. Copy this dimension from the exact profile.
- 03
Set layout and fastening assumptions
Choose horizontal or vertical installation, then enter stock length, support spacing, and fasteners per support from the approved installation plan.
- 04
Add waste and actual prices
Increase waste for short walls, end matching, defects, color selection, and complex cuts, then enter current board and fastener-package prices if useful.
Worked example
Example: one 16 ft by 8 ft wall
A 16 ft by 8 ft wall with 16 sq ft of openings has 112 sq ft of net coverage. A 6 in installed face requires 224 linear ft. With horizontal 16 ft runs, 8 ft stock, and 10% allowance, the cut plan rounds up to 31 boards and includes one butt joint per run.
Practical buying and overage guidance
Confirm installed face width, stock lengths, moisture content, acclimation, grade, finish, end matching, support layout, fastener type, corner and transition trim, electrical extensions, delivery, return rules, and whether boards from different lots will be visually compatible.
Continue the project
Frame & Finish a Room
Plan wall framing, insulation, drywall, paint, flooring, baseboard, trim, materials, supplies, and contractor pricing in one workflow.
Open the project workflow →Calculation sources and review
Primary references and formula assumptions are linked so you can verify them against the selected product, supplier, and adopted local requirements.
Internal formula review completed July 13, 2026. What this review covers
- UFP-Edge - Installation Resources (opens in a new tab)
Manufacturer-specific acclimation, fastening, layout, and finishing guidance.
- American Wood Council - Publications (opens in a new tab)
Wood-product use and fire-performance context; decorative boards are not structural sheathing.
Frequently asked questions
Should I use nominal board width or installed face width?
Use installed face coverage: the width left visible after the overlap or joint is engaged. Nominal width usually overstates coverage and can undercount boards.
Does orientation change the amount of shiplap?
Net coverage is area-based, but orientation changes run length, joints, backing needs, and how many full-height or full-width cuts fit in each stock board. The calculator compares pooled linear footage with an orientation-aware cut plan and uses the larger purchase count.
How much shiplap waste should I include?
Waste depends on stock length, wall layout, defects, finish selection, end matching, corners, openings, and whether offcuts can start another run. Edit the allowance for the actual cut plan.
Are shiplap boards structural sheathing?
Not unless the approved assembly and product documentation specifically say so. Decorative shiplap should not be assumed to provide bracing, shear resistance, fire rating, or required wall protection.
Does the fastener count replace manufacturer instructions?
No. It is a purchase estimate from entered support spacing and fasteners per crossing. Substrate, orientation, board thickness, species, moisture, fire assemblies, and manufacturer requirements control fastening.