Deck Railing Calculator

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Calculate the materials needed for your deck railing including balusters (spindles), railing posts, top rail, and bottom rail. Enter the total railing length and baluster spacing to get accurate material counts that meet building code requirements.

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Enter Your Measurements

Results

Balusters

133

balusters

Railing Posts

8

posts

Top Rail Pieces

7

pieces

Bottom Rail Pieces

7

pieces

Post Caps

8

caps

Railing Sections

7

sections

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Formula

Balusters per Section = (Section Length × 12 ÷ Spacing) + 1 | Posts = Sections + 1

How to Use This Calculator

How to Use

  1. 1

    Measure the total length of railing needed in feet.

  2. 2

    Enter the baluster spacing center-to-center (maximum 4 inches per most codes).

  3. 3

    Enter the baluster width (1.5 inches for standard 2x2 balusters).

  4. 4

    Enter the desired section length between posts (6 to 8 feet is typical).

Frequently Asked Questions

Frequently Asked Questions

What is the maximum gap between balusters?

Building codes require that a 4-inch sphere cannot pass through baluster openings. With 1.5-inch balusters on 4-inch centers, the gap is 2.5 inches, which meets code.

How tall does deck railing need to be?

Most building codes require deck railing to be at least 36 inches high for decks up to 30 inches above grade, and 42 inches for higher decks. Check your local code for specific requirements.
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About This Calculator

This calculator uses the formula: Balusters per Section = (Section Length × 12 ÷ Spacing) + 1 | Posts = Sections + 1. All calculations follow industry-standard methods. Results are estimates — always verify with a licensed professional for structural or code-compliant work.

Built and maintained by the CalcSmart team. Last updated March 2026.

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