Gravel Cost Calculator

Deck Calculator

Estimate the square footage, decking boards, and joists you need to build a deck based on its length, width, and board width.

ft
ft
in

Standard 5/4 decking boards are about 5.5 in wide after milling.

Covers angled cuts, staggered seams, and defects. 10% works for most simple decks.

How this is calculated

Deck area is length × width. Decking linear footage is the area divided by the board's actual face width, which approximates board count while ignoring the small gaps typically left between boards for drainage. We add your selected waste percentage for angled cuts, staggered seams, and defects, then convert to a board count assuming standard 12 ft boards. Joist count assumes standard 16 in on-center spacing across the deck's width, with joists running the full length — actual framing should be confirmed against local building code and span tables for your joist size and species.

Example calculation

A 16 ft × 12 ft deck is 192 ft². With 5.5 in boards and 10% waste, that's about 461 linear feet, or 39 boards at 12 ft each, plus 10 joists at 16 in on-center.

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Frequently asked questions

10% is typical for a simple rectangular deck. Diagonal patterns, picture-frame borders, or decks with many cutouts often need 15% or more.