Conduit Fill Calculator-NEC

NEC conduit fill calculator for electricians, apprentices, and electrical engineers.

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.