Equal Spacing Formula
Gap = (Total Length − (Items × Width)) ÷ (Items − 1)
Items at Ends — No:
Gap = (Total Length − (Items × Width)) ÷ (Items + 1)
Centre-to-Centre: Gap + Item Width
Items at Ends: Select "Yes" if items are placed at both ends (e.g. fence posts). Select "No" if items are between the ends (e.g. balusters).
Equal Spacing Calculator — Posts, Balusters & Fixings
From balustrade spacing (max 125mm gap under NCC) to evenly distributing fixings, equal spacing is one of the most common on-site calculations. This calculator finds the exact centre-to-centre and gap distances for any number of items across any total length.
The Formula
- Items at both ends: Gap = (Total Length − (Items × Width)) / (Items − 1)
- Items between ends: Gap = (Total Length − (Items × Width)) / (Items + 1)
Common Applications
| Application | Typical Width | Max Gap | Reference |
|---|---|---|---|
| Balusters | 40–50mm | 125mm | NCC / AS 1170 |
| Fence palings | 65–100mm | Varies | Local council |
| Studs | 35–45mm | 450/600mm c/c | AS 1684 |
Frequently Asked Questions
How do I calculate equal spacing between posts?
Measure total distance, count posts, then: Gap = (Total − (Posts × Width)) / (Posts − 1). E.g., 5 posts of 90mm across 3,000mm: (3000−450)/4 = 637.5mm gap.
What is the max gap between balusters in Australia?
Under the NCC, the max gap must not allow a 125mm sphere to pass through.
Gap vs centre-to-centre?
Gap is the clear space. Centre-to-centre = gap + item width. Always clarify which measurement a spec refers to.
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