Free Building Code Calculators for Contractors & DIYers
Build Code Calculator gives you instant code compliance checks based on IRC 2021 — no textbook required. Built by someone who has worked the trades for over 18 years and has looked up these numbers on the job site more times than anyone should have to.
What This Site Does
Every calculator on this site takes the measurements you already have and checks them against the relevant section of the International Residential Code (IRC) 2021. You get a clear pass or fail, the exact code section, and the specific minimum that applies to your situation.
The tools cover the measurements that come up most often in residential construction and renovation — the ones that get flagged at inspection, the ones that are easy to assume are fine and aren’t, and the ones where the code is more nuanced than a single number.
The Calculators
Accuracy & Disclaimer
The values in these calculators come directly from IRC 2021 tables and sections. They are updated when the code is amended and cross-referenced against published span tables and code text.
That said: these tools are for reference, not for permit applications. Your local Authority Having Jurisdiction (AHJ) may have adopted local amendments that differ from the IRC. Always verify with your building department before starting construction or pulling a permit.
Sister Sites
Contact
Found an error in a code value? Have a suggestion for a calculator that should exist but doesn’t? Get in touch.
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