Conduit Fill Calculator
Verifies number of conductors fit within conduit per NEC Chapter 9 Table 1 fill limits. Supports EMT, PVC, RMC, and more.
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Based on NEC Chapter 9, Tables 1, 4, and 5. Verify with your local AHJ.
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How to Use This Calculator
1. Select the conduit type and size. EMT is the most common for commercial work. PVC Schedule 40 is used for underground and exposed runs.
2. Add your wires. Select the gauge and quantity for each conductor group. The calculator sums the total cross-sectional area automatically.
3. Check the nipple box if applicable. Conduit nipples (24 inches or less) are allowed 60% fill instead of the standard 40%.
4. Read the result. If it fails, the calculator suggests the next conduit size up that will pass.
Frequently Asked Questions
What is the NEC conduit fill limit?
How many #12 THHN wires fit in 3/4 inch EMT?
Does the ground wire count for conduit fill?
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