Deck Railing Calculator

Deck Railing Code Requirements

Deck railings are one of the most code-regulated components of a deck build. The IRC requires a railing (guard) on any deck surface 30 inches or more above grade. The minimum height is 36 inches for residential decks (some jurisdictions require 42 inches). And balusters must be spaced so that a 4-inch sphere cannot pass between them — that's the child safety rule.

Railing posts must be securely attached to the deck framing — not just the decking surface. Through-bolted to the rim joist or inner joist is the standard method. Surface-mounted post brackets are acceptable if they're rated for the application. Posts should be spaced no more than 6–8 feet apart depending on the rail material and local code.

The Bottom Line

Free deck railing calculator. Posts, balusters, top and bottom rails for wood and composite deck railings. Accurate measurements prevent over-ordering and under-ordering — both cost you money and time. Enter your project dimensions above, add 10% for waste, and order with confidence.