Baluster spacing calculator
How many balusters a run takes at a maximum permitted gap.
Fill in the fields and the result will appear here automatically.
Calculates an evenly spaced run of equal-width balusters with equal gaps between them and at both ends. It finds the smallest count, starting at one, whose positive clear gap does not exceed your chosen limit. The limit comes from your project; the calculation does not certify a guard as safe.
How it works
Formula and logic
For n balusters of width b in run L: g = (L−n·b)/(n+1). Choose the smallest n from 1 to 10,000 satisfying 0 < g ≤ gmax; centre pitch p = b+g = (L+b)/(n+1). All dimensions are positive finite millimetres, with b < L.
Example
A 3000 mm run with 40 mm balusters and a 100 mm limit takes 21 balusters — an actual gap of 98.18 mm.
Fields and units
- Clear run between posts — mm
- Baluster width — mm
- Maximum gap — mm
How to use
- — Enter the clear run between the end supports in millimetres.
- — Specify baluster width and the clear gap allowed by your project.
- — Distinguish clear gap from centre pitch: pitch includes the baluster width.
Method and limitations
- Calculation method
- Formula and logic
- Limitation
- The limit comes from your project; the calculation does not certify a guard as safe.
FAQ
Why is there one more gap than balusters?
There are two end gaps as well as the spaces between balusters. Thus n balusters have n+1 equal clear gaps.
May the gap equal the limit?
Yes: the rule is no greater than the limit. L=300 mm, b=40 mm and a 130 mm limit give one baluster and two 130 mm gaps.
What does pitch mean with one baluster?
It is the theoretical repeat pitch b+g, here 170 mm. With one baluster there is no actual adjacent pair of centres.
Does this check guard requirements?
No. Height, loads, fixings and applicable restrictions are not checked. The model uses at least one and at most 10,000 balusters and rejects layouts with no positive gaps.