Which NEC tables does this conduit fill calculator use?

We use Chapter 9 Table 1 (allowable fill percentages), Table 4 (conduit areas), and Table 5 (conductor areas) aligned with the 2023 NEC.

Can I mix different wire sizes in one conduit?

Real installations often mix sizes; this tool models one wire size at a time. For mixed fills, calculate total conductor area manually or run separate checks per conductor group.

Does this include nipple exceptions?

No. Short conduit nipples (≤24 in.) have different rules in NEC 300.15(C). Treat this as a standard raceway fill check.

Field electrical

Conduit Fill Calculator

Calculate NEC-compliant conduit fill using Chapter 9 tables for EMT, PVC, and RMC.

Electrician routing cable through conduit on a commercial job site

Raceway inputs

Conduit type

Trade size

Insulation type

Wire size (AWG/kcmil)

Number of same conductors

How to use this conduit fill tool

Select conduit type and trade size (EMT, PVC Sch 40, or RMC).
Choose insulation type and AWG/kcmil size from NEC Chapter 9 Table 5.
Enter the number of identical conductors in the same raceway.
Review fill percentage against NEC Chapter 9 Table 1 limits (53% / 31% / 40%).

Disclaimer

This calculator is for planning only. Conduit fill rules depend on conductor type, nipples, and local amendments. A licensed electrician or engineer must verify compliance before installation.

Sources & references

NFPA 70 — National Electrical Code (Chapter 9)

Based on NFPA 70 (NEC) 2023 unless noted. Confirm the edition adopted locally.

Frequently asked questions

Which NEC tables does this conduit fill calculator use?: We use Chapter 9 Table 1 (allowable fill percentages), Table 4 (conduit areas), and Table 5 (conductor areas) aligned with the 2023 NEC.
Can I mix different wire sizes in one conduit?: Real installations often mix sizes; this tool models one wire size at a time. For mixed fills, calculate total conductor area manually or run separate checks per conductor group.
Does this include nipple exceptions?: No. Short conduit nipples (≤24 in.) have different rules in NEC 300.15(C). Treat this as a standard raceway fill check.