Conduit outside diameter chart
The outside diameter (OD) of each trade size, which is what a conduit’s gain, spacing and clearances are worked out from.
| Size | EMT | rigid (RMC) | IMC |
|---|---|---|---|
| 1/2" | 0.706" | 0.840" | 0.815" |
| 3/4" | 0.922" | 1.050" | 1.029" |
| 1" | 1.163" | 1.315" | 1.290" |
| 1-1/4" | 1.510" | 1.660" | 1.638" |
| 1-1/2" | 1.740" | 1.900" | 1.883" |
| 2" | 2.197" | 2.375" | 2.360" |
| 2-1/2" | 2.875" | 2.875" | 2.857" |
| 3" | 3.500" | 3.500" | 3.476" |
| 3-1/2" | 4.000" | 4.000" | 3.971" |
| 4" | 4.500" | 4.500" | 4.466" |
| 5" | — | 5.563" | — |
| 6" | — | 6.625" | — |
Why trade size isn’t the diameter
A trade size is a name, not a measurement: 1/2" EMT is about 0.7" across the outside, and 1/2" rigid about 0.84". Up to 2", EMT is smaller across the outside than rigid or IMC of the same trade size, and IMC is a little smaller than rigid. From 2-1/2" up, EMT and rigid have the same outside diameter.
Common questions
What is the outside diameter of 1/2" EMT?
0.706" (ANSI C80.3).
What is the outside diameter of 3/4" EMT?
0.922" (ANSI C80.3).
What is the outside diameter of 1" EMT?
1.163" (ANSI C80.3).
What is the outside diameter of 1-1/4" EMT?
1.510" (ANSI C80.3).
What is the outside diameter of 1/2" rigid (RMC)?
0.840" (ANSI C80.1).
What is the outside diameter of 3/4" rigid (RMC)?
1.050" (ANSI C80.1).
Get the marks for your bender
BendMate works this out from your bender’s radius and deduct, flags a bend that won’t work, and shows you every mark.