1-Inch Conduit Wire Fill Calculator
Free online tool • 2026 NEC Compliant
1-inch conduit (trade size 1") is commonly used for feeder runs, home runs, and service work. Use this calculator to determine the maximum number of conductors per the NEC 40% fill rule. Internal areas: 1" EMT = 0.864 in², 1" PVC Sch. 40 = 0.832 in².
Conductors
THHN / THWN-2Results
PASSTotal Conductors
3
Wire Area Used
0.0399 in²
Remaining Space
0.1733 in²
How to Use This Calculator
Select conduit type
Choose EMT, PVC, or another conduit type.
Select 1" trade size
The page pre-selects 1 inch conduit for you.
Add wire rows
Enter each wire gauge and quantity in your run.
Verify fill result
Confirm fill percentage is within NEC limits.
Frequently Asked Questions
How many 12 AWG wires fit in 1" EMT?
In 1" EMT (internal area 0.864 in², 40% limit = 0.346 in²), each 12 AWG THHN wire occupies 0.0133 in². You can fit approximately 26 conductors of 12 AWG THHN.
Specific Sizing Guides & Calculators
1-1/2" Conduit Wire Fill Calculator
Calculate how many wires fit in 1.5 inch conduit. Free 1-1/2" EMT, PVC Schedule 40/80, and RMC fill calculator per NEC 40% fill rule for 3+ conductors.
Cat 6 & Low-Voltage Conduit Fill Calculator
Calculate how many Cat 6 or Cat 6a ethernet cables fit inside EMT or PVC conduit. Compliant with NEC 40% fill rule for low-voltage communications wiring.
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