TrueFill: Conduit Fill
Conduit Fill Calculator
Only for iPhone
Free · Designed for iPhone. Not verified for macOS.
iPhone
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.
Ratings & Reviews
- This app hasn’t received enough ratings or reviews to display an overview.
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.
The developer, Nicole Nalley, indicated that the app’s privacy practices may include handling of data as described below. For more information, see the developer’s privacy policy .
Data Not Collected
The developer does not collect any data from this app.
Accessibility
The developer has not yet indicated which accessibility features this app supports. Learn More
Information
- Seller
- Nicole Nalley
- Size
- 5.8 MB
- Category
- Utilities
- Compatibility
Requires iOS 17.0 or later.
- iPhone
Requires iOS 17.0 or later. - Mac
Requires macOS 14.0 or later and a Mac with Apple M1 chip or later. - Apple Vision
Requires visionOS 1.0 or later.
- iPhone
- Languages
- English
- Age Rating
4+
- 4+
- Copyright
- © 2026 509 Electric LLC