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Decking Calculator
This assumes boards run along the deck length and adds 10% for cuts and waste.Enter your measurements
Board rows across the width × deck length, plus 10% allowance.
How this estimate works
Board rows across the width × deck length, plus 10% allowance.
Measure twice and use the same unit throughout. Product coverage, material density, installation patterns, and local requirements can change the quantity you need.
Quick answer
Estimate deck-board length by dividing the deck width by the installed board module, multiplying the number of rows by deck length, and adding cutting waste. Use the actual board width plus the required gap, not only the nominal lumber name.
Worked example
A 16 × 12 ft deck using a 5.5-inch installed module needs about 35 board rows. That is roughly 560 linear feet before allowing for cuts and layout waste.
Assumptions
- The deck is rectangular and boards run along its length.
- Board width represents the installed face width and planned spacing.
- The 10% allowance covers routine cuts, not structural framing or a diagonal layout.
What is installed board width?
Nominal lumber dimensions are not the same as finished dimensions. Use the measured face width of the product and include the spacing required by its installation instructions so the row count matches the actual layout.
Does the result include framing and fasteners?
No. The result estimates surface board length only. Joists, beams, posts, footings, blocking, stairs, guards, fasteners, and structural connectors need a code-compliant design and separate quantities.
When should waste be increased?
Diagonal boards, picture-frame borders, breaker boards, complex edges, and fixed stock lengths can create more offcuts. Sketch the board direction and available lengths before ordering.
Last reviewed September 22, 2026. Source: American Wood Council Prescriptive Residential Wood Deck Construction Guide. Product instructions take priority over a general estimate.