DeckCalc

Deck Post Calculator

A layout estimator for how many posts your deck-edge or railing sections need at a given spacing — not a structural capacity calculator.

Section 1
ft
in
in

This is your planning spacing, not a code-approved spacing.

Gate posts, corner posts you're adding beyond a shared endpoint, or anything else.

Add at least one section.

Post counting assumptions

Each section is assumed to need a post at both ends. Mark a section as connected to the previous one when they share a corner post, so that shared post is only counted once. Sections you leave unconnected are treated as separate, independent runs. This version doesn't support a later section connecting back to an earlier, non-adjacent one (closing a full loop) — model a closed loop as one connected run per side instead.

This is a layout estimator only — it does not calculate structural post capacity or footing size.

How it works

This uses the same section-based layout as the Railing Calculator: each section needs a post at both ends at your planning spacing, and marking a section as connected to the one before it means the shared corner post only gets counted once. Add posts you know about beyond what the sections already cover — gate posts, for instance — in the additional posts field.

Continue planning your deck

This website provides planning estimates and mathematical calculations for informational purposes. Actual material requirements can vary based on layout, product specifications, installation methods, site conditions, and applicable building codes. Structural dimensions and construction requirements should be verified using applicable codes, manufacturer instructions, approved plans, or a qualified professional before construction.