---
title: "Baluster Spacing Calculator"
description: "Equal baluster and spindle spacing that passes the 4-inch rule — with a visual layout. Free."
image: "https://nestingcalc.com/og-default.png"
url: "https://nestingcalc.com/baluster-spacing-calculator/"
locale: "en"
---

# Baluster Spacing Calculator

Equal baluster and spindle spacing that passes the 4-inch rule — with a visual layout. Free.

Enter the run between posts, the baluster width and the maximum gap your building code allows (100 mm / 4 in for the sphere rule). The calculator returns the minimum baluster count, the exact equal spacing and a mark for every baluster position.

Interactive calculator (open in browser): [https://nestingcalc.com/baluster-spacing-calculator/](https://nestingcalc.com/baluster-spacing-calculator/)

## FAQ

What is the 4-inch sphere rule?

Building codes (IRC and most national codes) require that a 100 mm / 4 in sphere cannot pass between balusters anywhere along a guard or stair rail. The calculator uses your max gap as this limit and spaces all gaps equally below it.

Why are my gaps smaller than the maximum?

Equal spacing looks best and installs fastest. The calculator adds balusters until every gap — including the two gaps next to the posts — is at or below your maximum, then divides the leftover space equally.

Should spacing be measured to center or edge?

Work with edges, not centers: mark the left edge of each baluster from the left post, as shown in the layout above. Centers drift when the baluster width is included by mistake.

## Related calculators

-   [Miter Angle Calculator](https://nestingcalc.com/miter-calculator/)

    Perfect miter cuts for corners and multi-sided frames — free.

-   [Linear Cutting Calculator](https://nestingcalc.com/linear-cutting-calculator/)

    Optimize cuts for bars, pipes and profiles — minimize waste, free.

-   [Rebar Calculator](https://nestingcalc.com/rebar-calculator/)

    Rebar weight, length and bars-per-tonne takeoff for any size list — free.

## Related guides

-   [Baluster Spacing: Code Rules and Equal Layout](https://nestingcalc.com/guides/baluster-spacing-code/)

    The 4-inch sphere rule, how many balusters you really need, and how to mark equal spacing without drift.

-   [Crown Molding Angles: 38°, 45° and 52° Spring Angle Charts](https://nestingcalc.com/guides/crown-molding-angles/)

    Miter and bevel settings for flat-cutting crown molding — charts for the three standard spring angles and for corners that are not 90°.

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