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Deck Board Area Allowance & Fastener Budget
Estimate boards or square profiles from deck area with the captured 10% allowance, plus area-based fastener counts and entered material cost.
- Formula & worked example
- Private in your browser
- No signup
Calculator inputs
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How to use this calculator
- Enter the known values in the units shown. Results update as you type.
- Where results are editable, change one to solve backwards. Lock a value to hold it fixed.
- Use the worked example to check the method. Reset restores the starting fields.
Private by default
Inputs and results stay in this browser tab. Bookify does not upload or store the values you enter.
Formula and method
A 4 m by 3 m deck using 20 cm by 3 m boards requires 22 boards under the fixed 10% area allowance. At $10 per board plus $25 in fasteners, the material subtotal is $245.
Boards = ceil[deck area / board face area × 1.10]; fastener estimate = ceil[deck area in ft² × chosen density]
Worked example
Enter these known values and leave the other values blank.
- Length
- 4 m
- Width
- 3 m
- Board width / square-profile side
- Other
- Width
- 20 cm
- Enter board length
- 3 m
- Enter cost of one board
- 10 USD
- Total fastener cost for the project
- 25 USD
- Square footage (area)
- 12 m²
- Whole boards / profiles with 10% allowance
- 22
- Area-based screw or nail allowance
- 453
- Price for all boards
- 220 USD
- Board and fastener material subtotal
- 245 USD
Assumptions and limitations
- Board count divides total area by board face area and adds a fixed 10% allowance. It does not plan individual cuts, board orientation, joints, gaps, borders or reuse of offcuts.
- Use actual covering dimensions. The captured presets retain their listed widths; nominal lumber size can differ from actual finished dimensions.
- Fastener estimates use the captured densities of 3.5 screws/nails or 1.75 hidden clips per square foot. These are area allowances, not a fastening schedule based on joist spacing or a product specification.
- Enter the total fastener cost, not a per-pack price. The subtotal excludes substructure, railings, foundations, labor, delivery and tax. Square-profile mode retains the board-only estimate.
Common questions
Does the calculator design the deck structure?
No. It estimates covering materials under stated area assumptions. Joists, support spacing, fastener layout and local structural requirements need separate design information.
References
Bookify uses the exact 0.09290304 m² per square foot in fastener counts so a rounded conversion cannot undercount a ceiling boundary.
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