Conduit Fill Calculator

Need a conduit fill calculator or to figure out what size conduit you actually need? These tools can do it all and are built for the real-world mix of cables we see in low-voltage installs.

You can choose your fill percentage — 40%, 60%, or a custom rate — and select from standard EMT, RMC, and PVC conduits, or go beyond with Hilti Speed Sleeve Calculator, Modular Sleeves, and STI EZ Path Calculator. We built this tool with the sleeves and fittings we actually use in the field every day, not just what’s in the NEC book.

We’ve also preloaded dozens of cable types for quick calculations. From Cat5e to Cat8 (both UTP and STP), composite access control, coax RG-11 quad shield, Telco 25/50/100 pair, THHN, fire wire, and other low-voltage cable types.   They're all in there. You can even input your own cable diameters if you're working with something custom or unknown.

This conduit fill calculator is designed for techs, estimators, and engineers who need real answers fast — whether you’re roughing in, planning pull paths, or verifying raceway compliance on the job.