What conduit fill means
Conduit fill is how much of a conduit's inside area the wires take up. The code limits it so wires can be pulled without damage and do not overheat.
Where it matters on a electrical job
Overfilled conduit is hard to pull and an inspection fail. Check fill before you buy the conduit size, especially when adding circuits to an existing run.
What the model code says
- The maximum number of conductors in conduit or tubing follows the code's fill tables. (IRC 2021, Chapter 39)
Check which code edition your building department enforces for conduit fill before you quote.
What it costs
For conduit fill, the closest koira.ai price is the rewiring a house cost guide, near $9,150 for a typical job and $6,650 to $11,500 for most. The guide shows its sources and what moves the price. The conduit fill calculator prices a job line by line.
Work it out
- Free calculator: Conduit fill calculator
- Cost guide: Rewiring a house cost
- Licensing: Electrical license rules by state
- Tools, templates and guides: Free electrical resources
Sources: 2021 International Residential Code, Chapter 39, Power and Lighting Distribution (ICC). Checked October 9, 2026.