Deck Board and Joist Calculator
Free carpentry tool

Deck Board and Joist Calculator

Enter the deck size and board width to see deck boards, joists, posts and fasteners to plan for.

These tools give planning-level estimates from typical values. They are not quotes, designs or engineering, and results depend on your actual materials, framing, access, local rules and conditions. Only a site visit can confirm what a project needs, and we give you a written scope and price before any work begins.

How it works

Four quick steps.

  1. 01

    Enter the deck size

    Length and width in feet.

  2. 02

    Pick the board width

    Five and a half inch boards are common.

  3. 03

    Set the joist spacing

    Sixteen inches is common.

  4. 04

    Read the counts

    Boards, joists, posts and screws to plan for.

Tips

  • Joist spacing depends on the decking material and the manufacturer instructions.
  • Always order extra boards for cuts and for future repairs.
  • A deck needs a flashed ledger and proper footings.
Questions

About this tool.

Is this a materials list?

No. It is a planning estimate. We measure on site and take off exact materials.

How far apart should joists be?

Sixteen inches on center is common, and some materials need less. We follow the product rules.

Does this include railings?

No. Railings, stairs and footings are planned separately.

Free estimate

Ready to start your carpentry project?

Call us and we will walk the space, talk through ideas and give you a clear plan and a written scope.

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