Conduit Fill Calculator - NEC

NEC conduit fill calculator. EMT, PVC, IMC sizes. THHN wire 14 AWG–1000 MCM.

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. Works 100% offline on the job site.

Whether you're pulling THHN through EMT 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.

CONDUIT FILL CALCULATOR FEATURES:
• 5 conduit types: EMT, IMC, RMC, PVC Schedule 40, PVC Schedule 80
• All standard trade sizes: 1/2" through 4"
• THHN/THWN-2 wire sizes: 14 AWG to 1000 MCM
• 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
• Suggests the next conduit size when you exceed fill capacity
• 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, IMC, RMC, PVC)
• NEC Chapter 9, Table 5 — Wire dimensions and areas (THHN, THWN-2)

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.