Deck fastener estimator

Deck Screw Calculator

Estimate deck screws and screw boxes from deck size, board width, gap, joist spacing, screws per joist, waste, and box count.

Units

Deck width across boards (ft)Deck length along joists (ft)Board width (in)Board gap (in)Joist spacing (in)Screws per joist hit Waste / extras (%)Screws per box Cost per box ($)

Screws to buy

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Screw boxes

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Board × joist hits

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Estimated cost

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Fastener schedule must match the decking

Confirm screw type, corrosion rating, manufacturer fastening pattern, edge distance, hidden-fastener system, and local deck requirements before installing.

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Deck screw formula

Board rows = deck width ÷ (board width + gap)

Joist rows = deck length ÷ joist spacing + 1

Screws = board rows × joist rows × screws per joist × (1 + waste %)

Example

A 12 ft by 16 ft deck with 5.5 in boards, 0.25 in gaps, 16 in joist spacing, two screws per joist, and 10% waste needs about 632 screws, or two 350-count boxes.Use the same layout logic with metric dimensions: boards across the width, joists along the length, then screws at every board-to-joist hit.

Deck Screw Calculator FAQ

How does this deck screw calculator work?+

It multiplies measured job dimensions by the coverage, spacing, or package yield you enter, adds waste, then rounds the buy quantity up. Screw count is based on every board-to-joist crossing.It multiplies measured job dimensions by the coverage, spacing, or package yield you enter, adds waste, then rounds the buy quantity up. Screw count is based on every board-to-joist crossing.

Should I use the default waste value?+

Use the default for a quick planning estimate, then raise it for cuts, odd layouts, breakage, bad access, or product-specific loss.Use the default for a quick planning estimate, then raise it for cuts, odd layouts, breakage, bad access, or product-specific loss.

Is this a bid or code approval?+

No. It is a material planning calculator. Verify product data, local code, structural requirements, electrical requirements, and supplier packaging before ordering or building.No. It is a material planning calculator. Verify product data, local code, structural requirements, electrical requirements, and supplier packaging before ordering or building.