Spindle Spacing Calculator

Building a deck, stair, or balcony railing? The Spindle Spacing Calculator determines how many spindles you need and how far apart to place them — while keeping gaps within the 4-inch building code limit. Enter your total railing length, spindle width, maximum gap, and post-to-spindle end spacing, then select your installation type to get the total spindle count, actual gap between spindles, center-to-center distance, and total spindle width.

inches

Distance between posts (post-to-post measurement)

inches

Width of each individual spindle

inches

Code typically requires 4 inches or less

inches

Distance from post to the first spindle

Results

Total Spindles Needed

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Actual Spacing Between Spindles

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Center-to-Center Distance

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Total Width of All Spindles

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Frequently Asked Questions

What is the maximum spacing for spindles?

Building codes typically require that gaps between spindles be no more than 4 inches to prevent children from getting their heads stuck. Always check your local building codes as requirements may vary by location.

How many spindles do I need for my railing?

The number of spindles depends on your railing length, spindle width, and required spacing. Use our calculator to determine the exact number needed for your specific project dimensions.

How do I evenly space spindles?

Divide the available space (total length minus spindle widths) by the number of gaps needed. Our calculator automatically determines the optimal spacing to ensure even distribution while meeting code requirements.

Does the angle of stairs affect spindle calculation?

For slanted stair railings, you'll need to measure the horizontal distance along the stair treads, not the angled length of the railing itself. Use this horizontal measurement in the calculator.

Can spindles be horizontal instead of vertical?

Yes, horizontal spindles are allowed in many areas, but the same 4-inch maximum spacing rule typically applies. Horizontal railings may have different code requirements, so check with local authorities.

What's the difference between spindles, balusters, and posts?

Posts are vertical supports that connect to the deck structure. Spindles (also called balusters) are the smaller vertical pieces between posts that provide the safety barrier.

How do I measure for spindle spacing on curved railings?

For curved railings, measure the arc length and use that as your total length. You may need to adjust spindle angles slightly to follow the curve properly.