Decking, Fencing & Timber calculator
Deck Post Calculator
Estimate a simple deck support-post grid from deck length, deck width and planned maximum post spacing in both directions.
Estimate a simple deck support-post grid from deck length, deck width and planned maximum post spacing in both directions. Start with measurements from the actual job and use manufacturer or supplier figures wherever the form asks for coverage, yield, density, spacing or pack size. Watch post spacing in both directions in particular. A simple grid count does not determine structural adequacy. Beam layout, loads, spans, footing positions and cantilevers can require a different post arrangement.
What you need to enter
The Deck Post Calculator uses the following project information to calculate the result.
- Deck length
- Deck width
- Post spacing along length
- Post spacing across width
Calculator result
Indicative post grid count
How the Deck Post Calculator works
Calculation logic: rows = ceil(length/spacing)+1; columns = ceil(width/spacing)+1; posts = rows × columns; layout estimator only. For support post count for a planned deck layout, the Deck Post Calculator uses that method after normalising the entered units. The output is then converted for display. The practical assumption that deserves the closest check is post spacing in both directions.
Deck Post Calculator worked example
Deck Post Calculator example: a 6 m × 4 m deck explored with maximum post spacing of 2 m in both directions creates a simple 4-by-3 grid, or 12 indicative post positions. Structural beam and footing design may change that layout. After calculating, compare the result with the job conditions and especially post spacing in both directions before rounding or selecting materials.
Important calculation assumptions
For support post count for a planned deck layout, a simple grid count does not determine structural adequacy. Beam layout, loads, spans, footing positions and cantilevers can require a different post arrangement.
Frequently asked questions
How should I collect the measurements for the Deck Post Calculator?
For support post count for a planned deck layout, measure deck length and width and enter the planned maximum post spacing in both directions. Treat the grid as a layout estimate only. This keeps the calculation tied to the actual job rather than a generic assumption.
Why should I prioritise post spacing in both directions over extra decimal precision in the Deck Post Calculator?
A sensible Deck Post Calculator result depends on getting post spacing in both directions right. A simple grid count does not determine structural adequacy. Beam layout, loads, spans, footing positions and cantilevers can require a different post arrangement.
Can the Deck Post Calculator replace a structural or code check?
Use the post grid only to explore layout and quantity. Final post positions, footing sizes, beam spans and cantilevers must follow the structural design. That is the practical way to carry the Deck Post Calculator result into the next step.