Electrical Conduit Types
The National Electrical Code recognizes several types of conduit (raceways) for enclosing electrical conductors. Each conduit type has different physical characteristics, internal dimensions, installation requirements, and permitted locations. The internal cross-sectional area of the conduit directly determines how many wires can fit inside per the NEC fill rules: 53% fill for 1 conductor, 31% for 2 conductors, and 40% for 3 or more conductors.
Below is a comparison of all six conduit types supported by this calculator, covering metal conduits (EMT, IMC, RMC, FMC) and non-metallic conduits (PVC Schedule 40 and PVC Schedule 80). Each type has a different internal diameter for the same trade size, which means the number of conductors that fit varies by conduit type. Click any conduit size to view a detailed fill chart with maximum conductor counts for every wire size.
Choosing the right conduit type depends on the installation environment, required physical protection, local code requirements, and budget. Indoor commercial projects typically use EMT for cost and ease of installation. Outdoor and underground runs often use PVC Schedule 40 or RMC. Industrial sites may require IMC or RMC for added durability. Flexible Metal Conduit (FMC) is reserved for specific applications where rigid conduit cannot be practically installed.
Electrical Metallic Tubing (EMT)
The most common conduit in commercial and residential construction. Lightweight, thin-walled steel tubing with compression or set-screw fittings. EMT offers the largest internal area per trade size among metal conduits, allowing the most conductors. Ideal for indoor exposed and concealed wiring.
| Trade Size | Internal Area (sq.in.) | Fill Chart |
|---|---|---|
| 1/2" | 0.304 | View fill chart |
| 3/4" | 0.533 | View fill chart |
| 1" | 0.864 | View fill chart |
| 1-1/4" | 1.496 | View fill chart |
| 1-1/2" | 2.036 | View fill chart |
| 2" | 3.356 | View fill chart |
| 2-1/2" | 5.858 | View fill chart |
| 3" | 8.846 | View fill chart |
| 3-1/2" | 11.545 | View fill chart |
| 4" | 14.753 | View fill chart |
Intermediate Metal Conduit (IMC)
A mid-weight threaded conduit that bridges the gap between EMT and RMC. IMC provides better physical protection than EMT while weighing about one-third less than RMC. It uses threaded connections and is suitable for both indoor and outdoor installations.
| Trade Size | Internal Area (sq.in.) | Fill Chart |
|---|---|---|
| 1/2" | 0.342 | View fill chart |
| 3/4" | 0.586 | View fill chart |
| 1" | 0.959 | View fill chart |
| 1-1/4" | 1.647 | View fill chart |
| 1-1/2" | 2.225 | View fill chart |
| 2" | 3.63 | View fill chart |
| 2-1/2" | 5.452 | View fill chart |
| 3" | 8.528 | View fill chart |
| 3-1/2" | 11.258 | View fill chart |
| 4" | 14.407 | View fill chart |
Rigid Metal Conduit (RMC)
The heaviest and most protective metal conduit. RMC has the thickest walls and smallest internal area for each trade size, but provides maximum protection for enclosed conductors. It is required in hazardous locations and is the standard for service entrance raceways in many jurisdictions.
| Trade Size | Internal Area (sq.in.) | Fill Chart |
|---|---|---|
| 1/2" | 0.314 | View fill chart |
| 3/4" | 0.549 | View fill chart |
| 1" | 0.887 | View fill chart |
| 1-1/4" | 1.526 | View fill chart |
| 1-1/2" | 2.071 | View fill chart |
| 2" | 3.408 | View fill chart |
| 2-1/2" | 5.135 | View fill chart |
| 3" | 8.085 | View fill chart |
| 3-1/2" | 10.694 | View fill chart |
| 4" | 13.631 | View fill chart |
PVC Schedule 40 Conduit (PVC-40)
The standard non-metallic conduit for underground and wet-location installations. PVC Schedule 40 resists corrosion, chemicals, and moisture. It uses solvent-cemented (glued) connections that create watertight joints. Less expensive and lighter than metal conduits.
| Trade Size | Internal Area (sq.in.) | Fill Chart |
|---|---|---|
| 1/2" | 0.285 | View fill chart |
| 3/4" | 0.508 | View fill chart |
| 1" | 0.832 | View fill chart |
| 1-1/4" | 1.453 | View fill chart |
| 1-1/2" | 1.986 | View fill chart |
| 2" | 3.291 | View fill chart |
| 2-1/2" | 4.695 | View fill chart |
| 3" | 7.268 | View fill chart |
| 3-1/2" | 9.737 | View fill chart |
| 4" | 12.554 | View fill chart |
PVC Schedule 80 Conduit (PVC-80)
A thicker-walled version of PVC conduit required wherever PVC is exposed above ground and subject to physical damage. PVC Schedule 80 has smaller internal area than Schedule 40 due to its thicker walls, reducing conductor capacity. It offers better impact resistance and can be threaded.
| Trade Size | Internal Area (sq.in.) | Fill Chart |
|---|---|---|
| 1/2" | 0.217 | View fill chart |
| 3/4" | 0.409 | View fill chart |
| 1" | 0.688 | View fill chart |
| 1-1/4" | 1.237 | View fill chart |
| 1-1/2" | 1.711 | View fill chart |
| 2" | 2.874 | View fill chart |
| 2-1/2" | 4.119 | View fill chart |
| 3" | 6.442 | View fill chart |
| 3-1/2" | 8.688 | View fill chart |
| 4" | 11.258 | View fill chart |
Flexible Metal Conduit (FMC)
A spirally-wound interlocking metal conduit that provides flexibility for routing around obstacles and making final connections to vibrating equipment. FMC (Greenfield) is used for motor connections, recessed lighting, and anywhere rigid conduit would be impractical. Typically limited to dry locations.
| Trade Size | Internal Area (sq.in.) | Fill Chart |
|---|---|---|
| 1/2" | 0.314 | View fill chart |
| 3/4" | 0.533 | View fill chart |
| 1" | 0.86 | View fill chart |
| 1-1/4" | 1.496 | View fill chart |
| 1-1/2" | 2.04 | View fill chart |
| 2" | 3.356 | View fill chart |
| 2-1/2" | 5.858 | View fill chart |
| 3" | 8.846 | View fill chart |
| 3-1/2" | 11.545 | View fill chart |
| 4" | 14.753 | View fill chart |