Deck Railing Calculator
Add each straight railing section and mark which ones share a corner post, to get a post count that doesn't double-count shared corners.
This is your planning spacing, not a code-approved spacing.
Gates or anything else not already covered by section endpoints.
Only if you're using fixed-length railing panels rather than individual balusters.
Add at least one section.
›Calculation details
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.
How it works
Each section on its own would need a post at both ends. But when two sections meet at a corner, that corner is really one post, not two — so marking a section as “connects to the previous section” tells the calculator to count that shared post once instead of twice. A railing with no corners at all (every section independent) gets the same total as simply adding up each section's post count on its own.
FAQ
My deck railing goes around three sides — how do I enter that?
Add one section per straight side, in order around the deck, and mark sections 2 and 3 as connecting to the one before them. Leave the very first section unmarked — there's nothing before it to connect to.
What about a stair opening in the middle of a run?
Enter the two sides of the opening as separate sections and leave the one after the gap unmarked, so it's treated as its own independent run rather than connected through the opening.
When should I enter a panel length?
Only if you're using pre-made railing panels with a fixed length, rather than spacing individual balusters yourself — panel count is calculated separately from post count and isn't assumed otherwise.