Deck planning tool
16x20 Deck Material Calculator
Use the 16 × 20 ft preset as a starting point for a 320-square-foot rectangular deck and adjust the material settings for your product.
Project planning calculator
Decking Material Estimator
Estimate boards, decking linear footage, joists, and fasteners for a rectangular deck. Enter actual board dimensions for a more useful result.
Project dimensions
Use feet for project and board lengths; use inches for widths and spacing.
Material estimate
Rounded up to whole purchasable quantities.
Deck area
320 sq ft
Deck-board rows
34
Decking to purchase
748 linear ft
16-ft boards
47
Estimated joists
16
Joist material
256 linear ft
Deck fasteners
About 1,197
90-count fastener boxes
14
How this result was calculated
- Rows = deck width across the boards divided by actual board width plus gap, rounded up.
- Decking = rows × board run length × 1.1 for waste.
- Board pieces = decking linear feet divided by stock board length, rounded up.
- Joists are placed perpendicular to the deck boards at the selected on-center spacing.
- Fasteners assume two fasteners at every board-to-joist intersection.
Building it yourself?
Shop your material list
Use the estimate above as a starting quantity, then verify dimensions and compatibility on the retailer product page.
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What to check before buying
- A 16 × 20 ft rectangle covers 320 square feet before stairs, borders, and other features.
- Longer runs can create butt joints when stock boards are shorter than the deck run.
- Complex borders and diagonal layouts normally require a larger waste allowance.