Baluster Spacing Calculator
Standard Baluster Layout
Calculate number of balusters and spacing for a railing section
Total Railing Project
Calculate total balusters needed for an entire railing project
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Formula
Balusters = ceil((Clear Span - Max Gap) / (Baluster Width + Max Gap)) | Actual Gap = (Clear Span - N × Width) / (N + 1)
Frequently Asked Questions
What is the code for baluster spacing?
The IRC (International Residential Code) requires that a 4-inch sphere cannot pass through any opening in the railing system. This means the clear gap between balusters must be less than 4 inches. This applies to deck railings, stair railings, and balcony guards.
How many balusters do I need per foot?
With standard 1.5-inch balusters and 3.75-inch gaps (under the 4-inch maximum), you need approximately 2-3 balusters per foot of railing. The exact number depends on your baluster width and desired gap.
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