Baluster Calculator
Construction & Home ImprovementCalculate the number of balusters needed for a railing, kept within the IRC 4-inch maximum gap rule.
Balusters Needed
Number of balusters needed along the railing run.
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Construction & Home Improvement calculators
Calculator Stats
Creators
Odeh Ahwal0people find this calculator helpful
Views
Helpful
Saved
Embeds
Construction & Home Improvement calculators
Frequently Asked Questions
How is baluster count calculated?
The total post width is subtracted from the railing length to get the space actually available for balusters and their gaps. That remaining length is divided by the width of one baluster plus one gap, giving the number of balusters that fit.
Why 4 inches for spacing by default?
The International Residential Code requires that a 4-inch sphere cannot pass through any opening in a guardrail, the same rule used in this site's Spindle Spacing Calculator. Using that maximum spacing here gives the fewest balusters that still meets the common code requirement; check your local code for the exact figure.
Should I round the baluster count up or down?
Round up, and let the final spacing come out very slightly tighter than the maximum. Rounding down would leave a gap wider than intended between the last two balusters.
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