Conduit Fill Calculator Pro

Answer the three questions of a pull on one screen: Does the bundle fit the pipe? What published trade size fits? How much room is left?

WireFill calculates conduit fill from NEC Chapter 9 and shows the arithmetic behind every result. Choose the NEC edition used on the job—2017, 2020, 2023, or 2026—then select the raceway and add each conductor by quantity, size, and insulation.

CALCULATE THE PULL

See the live fill percentage, applicable limit, bore area, allowed area, used area, and room left or over.

WireFill also shows: • the smallest published trade size that fits the bundle • how many more of the selected conductor will fit • Table 1 limits for one, two, or three-or-more conductors • the applicable 24-inch nipple rule • the Note 7 rounding allowance

Each conductor can be marked as not current carrying. Its area still counts toward conduit fill, while it is excluded from the current-carrying conductor count.

SHOW THE MATH

Open a complete record with: • the raceway area and circle equation • the permitted fill calculation • each conductor’s area and total occupied area • the resulting fill percentage and verdict • citations for the selected NEC edition

When more than three current-carrying conductors share the raceway, WireFill displays a separate notice that ampacity adjustment may be required. That calculation is not performed by the app.

SUPPORTED DATA

WireFill supports all thirteen raceway families published in Chapter 9 Table 4: EMT, IMC, RMC, ENT, PVC Schedule 40, PVC Schedule 80, PVC Type A, PVC Type EB, FMC, LFMC, LFNC-A, LFNC-B, and LFNC-C.

Published trade sizes are available from 3/8 inch through 6 inches where the selected raceway type and edition provide them.

Conductors are available from 14 AWG through 2000 kcmil across the supported Table 5 insulation groups. Compact stranded conductors from Table 5A are included where published.

SAVE AND SHARE

Name a calculation and reopen it with the raceway and conductors restored. Saved jobs can be duplicated or deleted.

WireFill Pro allows you to keep more than one saved job and export or share the complete calculation record as a PDF.

BUILT FOR THE JOBSITE

WireFill works fully offline. Calculations, saved jobs, and settings stay on the device. Nothing entered about a pull leaves the phone.

The app uses imperial units to match NEC Chapter 9 and is available in English and Spanish.

WireFill calculates conduit fill only. It does not calculate ampacity, ambient correction, adjustment factors, voltage drop, box fill, bending, or electrical loads. It supports listed Table 5 single conductors, not multi-conductor, MC, or NM cable. It does not provide Canadian Electrical Code or IEC calculations.

WireFill is an independent calculation aid based on published NEC Chapter 9 figures. NEC and National Electrical Code are registered trademarks of the National Fire Protection Association. WireFill is not affiliated with or endorsed by the NFPA and does not replace the code book, an inspection, professional judgment, or the authority having jurisdiction.

FREE

The free version includes the complete calculator, all supported raceways and conductors, four NEC editions, live results, Show the Math with citations, and one named job kept across restarts.

WIREFILL PRO

WireFill Pro unlocks storage for additional saved jobs, PDF export, and PDF sharing. If Pro expires, saved jobs remain readable; only adding another job is blocked.

Advanced job storage and PDF features require WireFill Pro.
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