509 Box Fill: NEC 314
NEC Box Fill Calculator
Free · Designed for iPad. Not verified for macOS.
Calculate NEC 314.16 box fill and 314.28 pull/junction-box sizing in seconds. Free for electricians, journeymen, and apprentices.
Calculate box fill per NEC 314.16 and pull/junction-box minimum dimensions per NEC 314.28 in seconds. 509 Box Fill is a fast, local-first field calculator built for electricians, journeymen, and apprentices.
Enter conductor counts, clamp and device allowances, and equipment grounds to get the required cubic-inch fill and pass/fail status against a standard or custom box volume. Switch to Min Box to find the smallest standard box that fits. Use Pull Box to calculate minimum box dimensions for straight and angle/U-pull raceway entries.
Designed for quick use:
• NEC 314.16(B) conductor volume allowances
• NEC 314.16(A) standard box volumes with pass/fail result
• Min Box recommends the smallest standard box that fits
• NEC 314.28 pull and junction box sizing for straight and angle/U pulls
• Light and dark mode
• Suite accent color picker
• NEC reference citations on every work line
• Local-first settings; no account or sign-in required
509 Box Fill is a field calculator. Always verify against the NEC adopted in your jurisdiction.
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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
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Information
- Seller
- Nicole Nalley
- Size
- 2 MB
- Category
- Utilities
- Compatibility
Requires iOS 15.0 or later.
- iPhone
Requires iOS 15.0 or later. - iPad
Requires iPadOS 15.0 or later. - iPod touch
Requires iOS 15.0 or later. - Mac
Requires macOS 12.0 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