Baluster Spacing Calculator
Enter your railing length, baluster width, and maximum gap to get the number of balusters and the exact, evenly distributed spacing that keeps every gap under the 4-inch code limit.
Results
- Balusters needed
- 17
- Even gap between
- 3.917 in
- Gaps (incl. ends)
- 18
Estimates only. Round up and buy a little extra to account for waste, spills, and breakage.
Enter your railing length, baluster width, and maximum gap to get the number of balusters and the exact, evenly distributed spacing that keeps every gap under the 4-inch code limit.
How to use the baluster spacing calculator
- Enter the railing length in in.
- Enter the baluster width in in.
- Enter the maximum gap in in.
- Optionally add a price to estimate the total project cost.
- Read your quantities instantly — no sign-up, and you can print the estimate to take to the supplier.
Worked example
Inputs
- Railing length
- 96 in
- Baluster width
- 1.5 in
- Maximum gap
- 4 in
Results
- Balusters needed
- 17
- Even gap between
- 3.917 in
- Gaps (incl. ends)
- 18
Using the example values above, the baluster spacing calculator returns 17 (balusters needed). Change any field to match your own project and the numbers update instantly.
Formula
Balusters = ceil((railing length − gap) ÷ (baluster width + max gap)). Even gap = (railing length − balusters × width) ÷ (balusters + 1).
Frequently asked questions
- How far apart should balusters be?
- Building codes require that a 4-inch sphere cannot pass between balusters, so keep every gap under 4 inches.
- How do I space balusters evenly?
- Find the minimum baluster count that keeps gaps under 4 inches, then distribute the leftover space equally across all gaps including the two ends.
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