BalustradeCalc

Baluster spacing is the clear gap between each vertical baluster (or spindle) in a balustrade. Getting it right matters for both safety and aesthetics - too wide and it fails compliance, too narrow and you waste materials and time on site.

In Australia, the National Construction Code (NCC Volume Two, Clause 3.9.2) and AS 1657:2018 set the maximum allowable gap at 125mm. This is measured as the clear opening between adjacent balusters, not centre-to-centre. For stair runs, the critical measurement is the horizontal gap (measured perpendicular to the balusters), which is always larger than the on-rake gap due to the angle. A spacing that looks compliant on the rake may actually exceed 125mm when measured horizontally.

BalustradeCalc handles all common balustrade configurations: flat runs (decks, balconies, level walkways) and stair runs, with standard spacing, against-post mounting, and tapered balusters. Use forward calculation when you know how many balusters you have and need the gap, or reverse calculation when you know the gap you want and need the baluster count.