How many 12 gauge wires fit in 3/4 inch conduit?

A 3/4 inch EMT conduit holds up to 16 THHN wires of 12 AWG at 40% fill (NEC 2023, Chapter 9 Table 1). The same trade size holds 15 wires in PVC Schedule 40, 12 in PVC Schedule 80 and 16 in rigid metal conduit (RMC).

12 AWG THHN wires in 3/4 inch conduit by conduit type

12 AWG THHN wires in 3/4 inch conduit at 40% fill
Conduit	Inside area, in²	12 AWG THHN wires
Electrical metallic tubing (EMT)	0.533	16
Rigid PVC conduit, Schedule 40	0.508	15
Rigid PVC conduit, Schedule 80	0.409	12
Rigid metal conduit (RMC)	0.549	16

How the 40% conduit fill is calculated

Wires = inside area × 40% ÷ area of one wire. One 12 AWG THHN wire is 0.0133 in². In 3/4 inch EMT: 0.533 in² × 40% ÷ 0.0133 in² = 16.03, rounded down unless the decimal is 0.8 or more, so 16 wires.

Why the wire count is not the number of circuits

The count is a physical limit on how many wires can be pulled without damaging the insulation. It is not the number of circuits you may run: when more than three current-carrying conductors share a conduit, their ampacity must be reduced, so a full conduit of 12 AWG wire usually cannot carry 20 A on every circuit.

Ground wires count toward the fill. Different insulation types have different areas; the wire counts on this page are for THHN/THWN-2 insulation, the most common building wire in conduit.

Related wire size, circuit and conduit answers

Sources

NFPA 70, National Electrical Code (2023): Percent of cross section of conduit and tubing for conductors, Chapter 9 Table 1
NFPA 70, National Electrical Code (2023): Dimensions and percent area of conduit and tubing, Chapter 9 Table 4
NFPA 70, National Electrical Code (2023): Dimensions of insulated conductors, Chapter 9 Table 5

Compared with 4 published documents, last on 2026-11-13

Carlon / Thomas & Betts (ABB) (catalog (edition not stated)): General information: wire fill based on Chapter 9 Table 1 — Conduit fill percentages
Florida International University (course notes, NEC edition not stated): Chapter III, Electrical Wiring Components (Figure 3.18, area of THHN conductors) — THHN areas for 14 to 6 AWG; the larger sizes match a training reproduction of the same table
Southwire Company, Power Cable Installation Guide (2005 (cites 2005 NEC)): Dimensions and percent area of conduit and tubing, Table 8 (EMT, rigid PVC Schedule 40 and 80) — Fill percentages and internal areas of EMT, PVC Schedule 40 and Schedule 80
Wheatland Tube (2022): Rigid Metal Conduit Submittal Sheet, weights and dimensions — Rigid metal conduit inside diameters; the areas follow from them

Calculated by Calculate.diy with the method of the National Electrical Code® (NEC®), 2023 edition; not the NEC text. Methodology. For planning only: check local code and use a licensed electrician.