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    Deck Calculator

    Calculate deck boards, joists, beams, posts and screws with this free online deck calculator. Enter deck size and board width for a full material list.

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    Found it useful? Share Deck Calculator

    Free, no sign-up, works in the browser — send it to a friend or add it to your site.

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    How to use Deck Calculator

    1. 1Choose feet and inches or metres and millimetres
    2. 2Enter the deck length and width, board width, gap, board length and joist spacing
    3. 3Read the number of deck boards, joists, beams, posts and screws, and add a board price to estimate the cost

    Frequently asked questions

    How many deck boards do I need for a 16 x 12 deck?▾

    With 5.5 inch boards, a 3/16 inch gap and 16 ft boards running along the 16 ft side, you need 26 rows, or about 29 boards including 10% waste.

    How many joists does a deck need?▾

    At the standard 16 inches on center, divide the deck length in inches by 16 and add one. A 16 ft deck needs 13 joists.

    How many screws do I need for decking?▾

    Use two screws per board at every joist. A 16 x 12 ft deck with 26 rows of boards over 13 joists needs about 676 screws, so buy a little extra.

    Embed Deck Calculator on your website▾

    Paste this snippet into your page. The embedded tool runs in your visitor's browser and shows a small “Powered by clkr.work” link.