Conduit Fill Calculator-NEC

About this app

NEC conduit fill calculator for electricians, apprentices, and electrical engineers. Calculate conduit fill percentages instantly using official NEC Chapter 9 data - Tables 1, 4, and 5. This electrical raceway calculator supports all conduit types and wire sizes. Works 100% offline on the job site. Whether you're pulling THHN through EMT, running FMC to a motor, or sizing PVC for a big commercial run, this conduit fill calculator gives you accurate NEC-compliant results in seconds. Use it as your portable conduit fill chart and raceway fill reference, faster than looking up wire count tables manually - perfect for residential and commercial installations. CONDUIT FILL CALCULATOR FEATURES: - 13 conduit types: EMT, ENT, FMC, IMC, LFNC-A, LFNC-B, LFMC, RMC, PVC Schedule 40, PVC Schedule 80, PVC Type A, PVC Type EB, HDPE - Trade sizes from 3/8" through 6" - 15 wire insulation types: building wire (THHN/THWN-2, XHHW-2, THW, RHH/RHW-2, USE-2, TW), fixture wire (TFFN/TFN, PF, PGF, PAF, PTF, ZF, SF-1, SF-2, RFH-2, FFH-2, KF-1) and high-temperature FEP, FEPB, PFA, PFAH, TFE - Wire sizes: 18 AWG to 1000 MCM (16/18 AWG for fixture wire) - AWG and mm² (metric) wire display - NEC Table 1 fill rules: 53% (1 wire), 31% (2 wires), 40% (3+ wires) - Visual PASS/FAIL indicator with fill percentage - Shows how many more wires you can add - Auto-suggests the smallest conduit size that fits your wires - even when the current size already passes - Nipple mode: conduit nipples up to 24 in use the NEC 60% fill allowance (Chapter 9, Note 4) - Mix different wire sizes in the same conduit fill calculation PRO FEATURES (one-time purchase): - No ads - clean interface for professionals - Save conduit fill calculation history - Export calculations as PDF reports for permits and records - Dark theme support BUILT FOR ELECTRICIANS ON THE JOB SITE: This conduit fill calculator is designed by electricians, for electricians. The interface is clean, fast, and works with one hand. Add wires, see your fill percentage, and move on - no complicated menus or unnecessary features. ACCURATE NEC CONDUIT FILL DATA: All conduit and wire areas are sourced from the NEC Chapter 9. Conduit fill percentages follow NEC Table 1 rules exactly: - 1 wire: 53% maximum fill - 2 wires: 31% maximum fill - 3 or more wires: 40% maximum fill NEC TABLES INCLUDED: - NEC Chapter 9, Table 1 - Percent fill for conduit and tubing - NEC Chapter 9, Table 4 - Conduit dimensions and areas (EMT, ENT, FMC, IMC, LFNC, LFMC, RMC, PVC, HDPE) - NEC Chapter 9, Table 5 - Wire dimensions and areas (THHN, XHHW, THW, RHW, USE, TW, TFFN, PF, ZF, SF, RFH, KF, FEP, PFA, TFE) PERFECT FOR: - Licensed electricians doing conduit fill calculations daily - Electrical apprentices studying for journeyman exams - Electrical engineers and designers - Electrical contractors bidding commercial and residential jobs - NEC code exam preparation - Anyone who needs a fast, accurate conduit fill calculator - Conduit sizing and wire count on the job site OFFLINE & PRIVACY: - Works 100% offline - no internet needed on the job site - No account required - No data collection - your calculations stay on your device Simplify your conduit fill calculations on the job site.

What's new: • 15 wire insulation types — added TFFN and the full fixture-wire family (PF, PGF, PAF, PTF, ZF, SF-1, SF-2, RFH-2, FFH-2, KF-1) plus high-temperature FEP, FEPB, PFA, PFAH, TFE • Added 16 AWG and 18 AWG sizes for fixture wire • Nipple mode: nipples up to 24 in fill to 60% (NEC Chapter 9, Note 4) • Auto-suggests the smallest conduit that fits — even when the current size passes • Bug fixes and stability improvements Send feedback to support@tradetools.dev.

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1. First observed Oct 16, 2026 · 4:59 PM $0.99