Conduit Fill Calculator

Conduit Fill Calculator supports both the National Electrical Code (NEC) and the Canadian Electrical Code (CEC). Fill limits follow NEC Chapter 9 Table 1 and CEC Table 8: 53% for 1 conductor, 31% for 2, and 40% for 3 or more.

The app supports EMT (Electrical Metallic Tubing), PVC Schedule 40, PVC Schedule 80, IMC (Intermediate Metal Conduit), and RMC (Rigid Metal Conduit). Conduit availability adjusts based on the selected code standard — for example, IMC is not available under the CEC.

For NEC: THHN, THWN, XHHW, USE, and RHW. For CEC: T90, RW90, and RPV90. Wire gauges range from 14 AWG up to 750 kcmil. All wire cross-sectional areas are sourced from NEC Table 5 and CEC Tables 6B/6K.

The app offers two input modes. Wires mode lets you specify a single wire type, gauge, and count. Circuits mode automatically computes the number of conductors based on your circuit type (e.g., single-phase, three-phase) including the equipment ground. You can also use Mixed Wire mode to add multiple wire type and gauge combinations in a single conduit.

Fill targets let you choose how aggressively you fill the conduit. Code Max (40%) uses the maximum fill allowed by code for 3+ conductors. Conservative (35%) gives a small margin below code max. Easy Pull (30%) provides extra room for easier wire pulling. The capacity and conduit sizing features respect whichever target you select.

When you have 4 or more current-carrying conductors in a conduit, the app displays an ampacity derating warning per NEC 310.15(C)(1) or CEC Rule 4-004. This reminds you that conductor ampacity must be reduced by a specific adjustment factor, which the app shows based on the number of conductors.

Yes. The conduit sizing feature shows you which conduit sizes will accommodate your selected wires within the active fill target. It lists all compatible sizes across the available conduit types so you can choose the best option for your installation.

Yes. Every calculation is automatically saved to your history (up to the 50 most recent entries). You can review past results at any time, and clear individual entries or the entire history whenever you like.

No. Conduit Fill Calculator is fully offline. All code data, conduit dimensions, and wire areas are built into the app. No account, login, or network connection is required.

Yes. All data stays entirely on your device. The app does not collect, transmit, or share any personal information. There are no analytics, tracking SDKs, or advertising frameworks. See our privacy policy for full details.

First, make sure you're running the latest version from the App Store. If the issue persists, please email us at forthemcreation@gmail.com with your device model and iOS version so we can investigate.