Baluster Calculator
Pitch is baluster width plus max clear gap. Spaces ceil from rail length over pitch. Balusters between ends equal spaces minus one. Estimate only, not a permit, code check, or engineered design.
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How to estimate baluster count
- Enter the clear rail length between end posts.
- Enter each baluster's width in the same unit.
- Enter the maximum clear gap you want between balusters.
- Read baluster count, space count, actual clear gap, and the pitch used. End posts are not in the count.
Baluster spacing count
Rail clear length with max gap target
| Pitch | balusterWidth + maxClear |
|---|---|
| Spaces | ceil(rail length / pitch) |
| Balusters | max(0, spaces - 1) |
| Actual clear | (rail - balusters × width) / spaces |
| Ends | End posts and newels are separate |
| Compliance | Estimate only. Local code may differ from the gap you typed. |
What this baluster count covers
The job is clear openings along one rail span. End posts stay outside the count. Stair rake geometry is not modeled. Deck boards sit on deck flooring. Fence runs use fencing.
How spacing is computed
pitch = balusterWidth + maxClear. spaces = ceil(length / pitch). balusters = spaces - 1 when spaces is at least 1. Actual clear redistributes leftover length across the spaces so the gap is never larger than your target under this sketch.
Code gaps and picket styles
Many residential notes talk about a 4-inch sphere rule. Your AHJ may use a different limit. Square, turned, and cable systems share gap intent but not this solid-width pitch model. Confirm on site.
Use cases
A 96-inch deck rail with 1.5-inch balusters and a 4-inch max clear. Comparing a tighter gap on the same rail. Not a stamped railing design.
Limits
No stair angle, no cable tension, and no post sizing. Estimate only, not a permit, code check, or engineered design. See the disclaimer.