TrueFill: Conduit Fill

About this app

TrueFill is a conduit-fill calculator built for electricians who want a clean answer and the math behind it - not just a number. Pick a raceway type, add your phase, neutral, ground, and spare conductors, and TrueFill returns the smallest passing trade size, the fill percentage against the allowable fill rule, the remaining area, and a full math trace you can check line by line. WHAT YOU GET - Smallest passing conduit and fill headroom in seconds - Conduit candidates compared, with pass/fail and room to spare - Show Math: conductor-area breakdown, assumptions, and source references - Save drafts and reopen the exact revision later - Quick-setup templates for 3-phase feeders, 1-phase branches, and control/spare runs BUILT FOR THE FIELD Dark, mobile-first, and fast to enter. Every result shows its inputs and assumptions so you can verify before you pull wire. This version ships with demo code data only. Results are clearly labeled as a demo/estimating aid and are intentionally blocked from final, export-ready, BOM, pricing, and bid-total use. Always verify against the NEC and your project documents. TrueFill is a calculation aid for qualified electrical professionals and is not a substitute for the NEC, a licensed engineer, or a code-compliance determination. From 509 Electric.

A fresh new look, built for the field. TrueFill's interface has been redesigned end to end - a cleaner, high-contrast dark theme that's easier to read on the jobsite: • Redesigned home screen with a focused conduit-fill workflow • Clearer results - sharper pass/fail, fill gauge, and conductor breakdown • Refined typography and layout throughout Same deterministic, NEC Chapter 9-referenced math you already trust - it just looks a lot better now.

Momentum comes from crawler snapshots for the tracked storefront. “Viral growth signal” means unusually fast recent rating gains; it is an indicator, not download data.

1. First observed Aug 16, 2026 · 11:02 AM Free