What does WireFillChart do?
WireFillChart is a free, browser-based NEC 2023 wire fill chart and conduit fill calculator for US electricians, inspectors, engineers and students. Pick a conduit type (EMT, IMC, RMC, PVC Schedule 40/80, FMC, LFNC, ENT), add THHN, THWN-2, RHH, RHW-2 or TW conductors, and read the live fill percentage, the NEC Chapter 9 Table 1 status (53/31/40% budgets, including Note 7 rounding) and a geometric jamming-risk hint; on overfill it recommends the next trade size. The site also has fill charts by conduit and wire type, box fill, pull box, conduit bend offset, voltage drop and wire size calculators, AWG/kcmil converters, and guides to NEC Chapter 9 Tables 4 and 5 and Table 310.16. No signup. Reference only: verify against the adopted code and your AHJ. Independent; not affiliated with NFPA.
Who should use WireFillChart?
engineers and students, inspectors, US electricians are the clearest fit based on how the product is positioned.
Best fit
Pricing: Free
Platforms: Web
How much does WireFillChart cost?
Free Check the provider’s own page for the latest pricing, packages and terms.
Details, pricing and availability can change. We use provider information, verified owner updates and editorial review where available. Check the provider’s own page before making a purchase, booking or important decision.
Profile last updated 9 Nov 2026.
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