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Electrical Pipe and Conduit Dimensions from 1/2" to 6"

 
"National Electrical Code" Conduit Chapters
EMT (Electrical Metallic Tubing, sometimes called "Thinwall") - Article 358
IMC (Intermediate Metal Conduit) - Article 342
RMC (Rigid Metal Conduit) - Article 344
FMC (Flexible Metal Conduit) - Article 348
PVC (Rigid Polyvinyl Chloride Conduit) - Article 352
ENT (Electrical Nonmetallic Tubing) - Article 362
LFMC (Liquidtight Flexible Metal Conduit) - Article 350
LFNC  (Liquidtight Flexible Non-Metallic Conduit) - Article 356
For more conduit code details also see Chapter 9, Table 4
See Informative Annex C in the back of the "National Electrical Code" for the allowable number of wires in each size conduit.
Trade
Size
USA
Trade
Size
Metric
1/2" 16
3/4" 21
1" 27
1 1/4" 35
1 1/2" 41
2" 53
2 1/2" 63
3" 78
3 1/2" 91
4" 103
5" 129
6" 155
At the bottom of this page, electrical conduit lengths are given with the metric equivalent.  There is also a hole saw chart for each size conduit.
The information below was derived from several sources and should not be considered precise.  Actual dimensions can vary slightly between manufacturers. This chart will be updated as more information becomes available.  Not responsible for errors and omissions.
Trade Size
USA
Trade Size
Metric
Inside Diameter
Inches
Inside Diameter
MM
Outside Diameter
Inches 
Outside Diameter
MM
Fractional Outside Diameter Inches Wall
Thickness 
Threads per inch
NPT
Size Opening Needed Into Box Drill for Tap
NPT
1/2"
EMT
16 0.622" 15.80 0.706" 17.93   0.042"
1.07mm
  7/8"
(Fitting opening)
Tap for fittings same as rigid
1/2"
IMC
16 0.660" 16.8 0.815"       14 7/8" 23/32" or 3/4"
1/2"
RMC
16 0.622" 15.80 0.840" 21.34 27/32"   14 7/8" 23/32" or 3/4"
1/2"
FMC
16 0.625" 16.1 0.920"         7/8"
(Fitting opening)
Tap for fittings same as rigid
1/2"
PVC
40
16 0.622" 15.80 0.840" 21.34   .109"   7/8"
(Fitting opening)
Tap for fittings same as rigid
1/2"
PVC
80
16 0.546" 13.87 0.840" 21.34   .147"   7/8"
(Fitting opening)
Tap for fittings same as rigid
1/2"
ENT
16     0.840"         7/8"
(Fitting opening)
 
1/2"
LFMC
16 .622"   0.840"         7/8"
(Fitting opening)
Tap for fittings same as rigid
1/2"
LFNC
16 0.622"   0.840"         7/8"
(Fitting opening)
Tap for fittings same as rigid
 
Click Pipe Size 1/2" 3/4" 1" 1 1/4" 1 1/2" 2" 2 1/2" 3" 3 1/2" 4" 5" 6"
Trade Size
USA
Trade Size
Metric
Inside Diameter
Inches
Inside Diameter
MM
Outside Diameter
Inches
Outside Diameter
MM
Fractional Outside Diameter Inches Wall
Thickness 
Threads per inch
NPT
Size Opening Needed Into Box Drill for Tap
NPT
3/4"
EMT
21 0.824" 20.93 0.922" 23.42   0.049"
1.25mm
  1 1/8"
(
Fitting opening)
Tap for fittings same as rigid
3/4"
IMC
21 0.864" 21.9 1.029"       14 1 1/8" 59/64" or 7/8"
3/4"
RMC
21 0.824" 20.93 1.050" 26.67 1 3/64"   14 1 1/8" 59/64" or 7/8"
3/4"
FMC
21 0.812" 20.9 1.105"         1 1/8"
(
Fitting opening)
Tap for fittings same as rigid
3/4" PVC
40
21 0.824" 20.93 1.050" 26.67   0.113"   1 1/8"
(
Fitting opening)
Tap for fittings same as rigid
3/4" PVC
80
21 0.742" 18.85 1.050" 26.67   0.154"   1 1/8"
(
Fitting opening)
Tap for fittings same as rigid
3/4"
ENT
21     1.050"         1 1/8"
(
Fitting opening)
 
3/4"
LFMC
21 0.820"   1.050"         1 1/8"
(
Fitting opening)
Tap for fittings same as rigid
3/4"
LFNC
21 0.820"   1.050"            
Click Pipe Size 1/2" 3/4" 1" 1 1/4" 1 1/2" 2" 2 1/2" 3" 3 1/2" 4" 5" 6"
 Click Here For The "Pipe Fitters Blue Book"
Trade Size
USA
Trade Size
Metric
Inside Diameter
Inches
Inside Diameter
MM
Outside Diameter
Inches
Outside Diameter
MM
Fractional Outside Diameter Inches Wall
Thickness 
 Threads per inch
NPT
Size Opening Needed Into Box Drill for Tap
NPT
1"
EMT
27 1.049" 26.64 1.163" 29.54 0.057" 1.45mm   1 3/8"
(
Fitting opening)
Tap for fittings same as rigid
1"
IMC
27 1.120" 28.1 1.290"       11.5 1 3/8" 1-5/32"or 1 1/8"
1"
RMC
27 1.049" 26.64 1.315" 33.4 1 5/16"   11.5 1 3/8" 1-5/32" or 1 1/8"
1"
FMC
27 1.020" 25.9 1.380"         1 3/8"
(
Fitting opening)
Tap for fittings same as rigid
1" PVC
40
27 1.049" 26.64 1.315" 33.40   .133"   1 3/8"
(
Fitting opening)
Tap for fittings same as rigid
1" PVC
80
27 .957" 24.31 1.315" 33.40   .179"   1 3/8"
(
Fitting opening)
Tap for fittings same as rigid
1"
ENT
27     1.315"         1 3/8"
(
Fitting opening)
 
1"
LFMC
27 1.041"   1.315"         1 3/8"
(
Fitting opening)
Tap for fittings same as rigid
1"
LFNC
27 1.041"   1.315"         1 3/8"
(
Fitting opening)
Tap for fittings same as rigid
 
Click Pipe Size 1/2" 3/4" 1" 1 1/4" 1 1/2" 2" 2 1/2" 3" 3 1/2" 4" 5" 6"
 
 
Trade Size
USA
Trade Size
Metric
Inside Diameter
Inches
Inside Diameter
MM
Outside Diameter
Inches
Outside Diameter
MM
Fractional Outside Diameter Inches Wall
Thickness 
Threads per Inch
NPT
Size Opening Needed Into Box Drill for Tap
NPT
1 1/4"
EMT
35 1.380" 35.05 1.510" 38.35   0.065"
1.65mm
  1 3/4"
(
Fitting opening)
Tap for fittings same as rigid
1 1/4"
IMC
35 1.468" 36.8 1.638"       11.5 1 3/4" 1-1/2"
1 1/4"
RMC
35 1.380" 35.05 1.660" 42.16 1 21/32"   11.5 1 3/4" 1-1/2"
1 1/4"
FMC
35 1.250" 32.4 1.630"         1 3/4"
(
Fitting opening)
Tap for fittings same as rigid
1 1/4" PVC
40
35 1.380" 35.05 1.660" 42.16   .140"   1 3/4"
(
Fitting opening)
Tap for fittings same as rigid
1 1/4" PVC
80
35 1.278" 32.46 1.660" 42.16   .191"   1 3/4"
(
Fitting opening)
Tap for fittings same as rigid
1 1/4"
ENT
35     1.660"         1 3/4"
(
Fitting opening)
 
1 1/4"
LFMC
35 1.380"   1.660"         1 3/4"
(
Fitting opening)
Tap for fittings same as rigid
1 1/4"
LFNC
35 1.380"   1.660"         1 3/4"
(
Fitting opening)
Tap for fittings same as rigid
 
Click Pipe Size 1/2" 3/4" 1" 1 1/4" 1 1/2" 2" 2 1/2" 3" 3 1/2" 4" 5" 6"
 
Trade Size
USA
Trade Size
Metric
Inside Diameter
Inches
Inside Diameter
MM
Outside Diameter
Inches
Outside Diameter
MM
Fractional Outside Diameter Inches Wall
Thickness 
Threads per Inch
NPT
Size Opening Needed Into Box Drill for Tap
NPT
1 1/2"
EMT
41 1.610" 40.89 1.740" 44.20   0.065"
1.65mm
  1 7/8"
(
Fitting opening)
Tap for fittings same as rigid
1 1/2"
IMC
41 1.703" 42.7 1.883"       11.5 1 7/8" 1-47/64" or 1 3/4"
1 1/2"
RMC
41 1.610" 40.89 1.900" 42.86 1 29/32"   11.5 1 7/8" 1-47/64" or 1 3/4"
1 1/2"
FMC
41 1.538" 39.1 1.950"         1 7/8"
(
Fitting opening)
Tap for fittings same as rigid
1 1/2" PVC
40
41 1.610" 40.89 1.900" 48.26   .145"   1 7/8"
(
Fitting opening)
Tap for fittings same as rigid
1 1/2" PVC
80
41 1.50" 38.10 1.900" 48.26   .200"   1 7/8"
(
Fitting opening)
Tap for fittings same as rigid
1 1/2"
ENT
41     1.990"         1 7/8"
(
Fitting opening)
 
1 1/2"
LFMC
41 1.575"   1.900"         1 7/8"
(
Fitting opening)
Tap for fittings same as rigid
1 1/2"
LFNC
41 1.575"   1.900"         1 7/8"
(
Fitting opening)
Tap for fittings same as rigid
 
Click Pipe Size 1/2" 3/4" 1" 1 1/4" 1 1/2" 2" 2 1/2" 3" 3 1/2" 4" 5" 6"
 
Trade Size
USA
Trade Size
Metric
Inside Diameter
Inches
Inside Diameter
MM
Outside Diameter
Inches
Outside Diameter
MM
Fractional Outside Diameter Inches Wall
Thickness 
Threads per Inch
NPT
Size Opening Needed Into Box Drill for Tap
NPT
2"
EMT
53 2.067" 52.50 2.197" 55.80   0.065"
1.65mm
  2 1/2"
(
Fitting opening)
Tap for fittings same as rigid
2"
IMC
53 2.170" 54.6 2.360"       11.5 2 1/2" 2-7/32" or 2 1/4"
2"
RMC
53 2.067 52.50 2.375" 60.33 2 3/8"   11.5 2 1/2" 2-7/32" or 2 1/4"
2"
FMC
53 2.040" 51.8 2.450"         2 1/2"
(
Fitting opening)
Tap for fittings same as rigid
2" PVC
40
53 2.067" 52.50 2.375" 60.33   .154"   2 1/2"
(
Fitting opening)
Tap for fittings same as rigid
2" PVC
80
53 1.939" 49.25 2.375" 60.33   .218"   2 1/2"
(
Fitting opening)
Tap for fittings same as rigid
2"
ENT
53     2.375"         2 1/2"
(
Fitting opening)
 
2"
LFMC
53 2.020"   2.375"         2 1/2"
(
Fitting opening)
Tap for fittings same as rigid
2" LFNC 53 2.020"   2.375"         2 1/2"
(
Fitting opening)
Tap for fittings same as rigid
 
Click Pipe Size 1/2" 3/4" 1" 1 1/4" 1 1/2" 2" 2 1/2" 3" 3 1/2" 4" 5" 6"
 
Trade Size
USA
Trade Size
Metric
Inside Diameter
Inches
Inside Diameter
MM
Outside Diameter
Inches
Outside Diameter
MM
Fractional Outside Diameter Inches Wall
Thickness 
Threads per Inch
NPT
Size Opening Needed Into Box Drill for Tap
NPT
2 1/2"
EMT
63 2.731" 69.4 2.875"     0.072"
1.83mm
  3"
(
Fitting opening)
Tap for fittings same as rigid
2 1/2"
IMC
63 2.597" 64.9 2.857"       8 3" 2-5/8"
2 1/2"
RMC
63 2.469" 62.71 2.875" 73.03 2 7/8"   8 3" 2-5/8"
2 1/2"
FMC
63 2.500" 63.5 3.060"         3"
(
Fitting opening)
Tap for fittings same as rigid
2 1/2" PVC
40
63 2.469" 62.71 2.875" 73.03   .203"   3"
(
Fitting opening)
Tap for fittings same as rigid
2 1/2" PVC
80
63 2.323" 59.00 2.875" 73.03   .276"   3"
(
Fitting opening)
Tap for fittings same as rigid
2 1/2" LFMC 63 2.480"   2.875"         3"
(
Fitting opening)
Tap for fittings same as rigid
 
Click Pipe Size 1/2" 3/4" 1" 1 1/4" 1 1/2" 2" 2 1/2" 3" 3 1/2" 4" 5" 6"
 
Trade Size
USA
Trade Size
Metric
Inside Diameter
Inches
Inside Diameter
MM
Outside Diameter
Inches
Outside Diameter
MM
Fractional Outside Diameter Inches Wall
Thickness 
Threads per Inch
NPT
Size Opening Needed Into Box Drill for Tap
NPT
3"
EMT
78 3.356" 85.24 3.500" 88.90   0.072"
1.83mm
  3 5/8"
(
Fitting opening)
Tap for fittings same as rigid
3"
IMC
78 3.216" 80.7 3.476"       8 3 5/8" 3-1/4"
3"
RMC
78 3.068" 77.93 3.500" 88.90 3 1/2"   8 3 5/8" 3-1/4"
3"
FMC
78 3.000" 76.2 3.560"         3 5/8"
(
Fitting opening)
Tap for fittings same as rigid
3" PVC
40
78 3.068" 77.93 3.500" 88.90   .216"   3 5/8"
(
Fitting opening)
Tap for fittings same as rigid
3" PVC
80
78 2.900" 73.66 3.500" 88.90   .300"   3 5/8"
(
Fitting opening)
Tap for fittings same as rigid
3"
LFMC
78 3.070"   3.500"         3 5/8"
(
Fitting opening)
Tap for fittings same as rigid
 
Click Pipe Size 1/2" 3/4" 1" 1 1/4" 1 1/2" 2" 2 1/2" 3" 3 1/2" 4" 5" 6"
 
Trade Size
USA
Trade Size
Metric
Inside Diameter
Inches
Inside Diameter
MM
Outside Diameter
Inches
Outside Diameter
MM
Fractional Outside Diameter Inches Wall
Thickness 
Threads per Inch
NPT
Size Opening Needed Into Box Drill for Tap
NPT
3 1/2"
EMT
91 3.834" 97.4 4.00"     0.083"
2.11mm
  4 1/8"
(
Fitting opening)
Tap for fittings same as rigid
3 1/2"
IMC
91 3.671" 93.2         8 4 1/8" 3-3/4"
3 1/2"
RMC
91 3.548" 90.12 4.00" 101.6 4"   8 4 1/8" 3-3/4"
3 1/2"
FMC
91 3.500" 88.9 4.060"         4 1/8"
(
Fitting opening)
Tap for fittings same as rigid
3 1/2" PVC
40
91 3.548" 90.12 4.000" 101.60   .226"   4 1/8"
(
Fitting opening)
Tap for fittings same as rigid
3 1/2"
LFMC
91 3.500"   4.000"         4 1/8"
(
Fitting opening)
Tap for fittings same as rigid
 
Click Pipe Size 1/2" 3/4" 1" 1 1/4" 1 1/2" 2" 2 1/2" 3" 3 1/2" 4" 5" 6"
 
Trade Size
USA
Trade Size
Metric
Inside Diameter
Inches
Inside Diameter
MM
Outside Diameter
Inches
Outside Diameter
MM
Fractional Outside Diameter Inches Wall
Thickness 
Threads per Inch
NPT
Size Opening Needed Into Box Drill for Tap
NPT
4"
EMT
103 4.334" 110.08 4.500" 114.30   0.083"
2.11mm
  4 1/2"
(
Fitting opening)
Tap for fittings same as rigid
4"
IMC
103 4.166" 105.4     4 1/2"   8 4 1/2" 4-1/4"
4"
RMC
103 4.026" 102.26 4.500" 114.30     8 4 1/2" 4-1/4"
4"
FMT
103 4.000" 101.6 4.560"         4 1/2"
(
Fitting opening)
Tap for fittings same as rigid
4" PVC
40
103 4.026" 102.26 4.500" 114.30   .237"   4 1/2"
(
Fitting opening)
Tap for fittings same as rigid
4" PVC
80
103 3.826" 97.18 4.500" 114.30   .337"   4 1/2"
(
Fitting opening)
Tap for fittings same as rigid
4"
LFMC
103 4.000"   4.500"         4 1/2"
(
Fitting opening)
Tap for fittings same as rigid
 
Click Pipe Size 1/2" 3/4" 1" 1 1/4" 1 1/2" 2" 2 1/2" 3" 3 1/2" 4" 5" 6"
Trade Size
USA
Trade Size
Metric
Inside Diameter
Inches
Inside Diameter
MM
Outside Diameter
Inches
Outside Diameter
MM
Fractional Outside Diameter Inches Wall
Thickness
 
Threads per Inch
NPT
Size Opening Needed Into Box Drill for Tap
NPT
5" PVC
40
129 5.047" 128.19 5.563" 141.30   .258"   5 5/8"  
5" PVC
80
129 4.813" 122.25 5.563" 141.30   .375"   5 5/8"  
Trade Size
USA
Trade Size
Metric
Inside Diameter
Inches
Inside Diameter
MM
Outside Diameter
Inches
Outside Diameter
MM
Fractional Outside Diameter Inches Wall
Thickness 
Threads per Inch
(NPT)
Size Opening Needed Into Box Drill for Tap
(NPT)
6" PVC
40
155 6.065" 154.05 6.625" 168.28   .280"   6 3/8"  
6" PVC
80
155 5.761" 146.33 6.625" 168.28   .432"   6 3/8"  
 
 
 
The standard length for electrical conduit is ten feet (10').  Some sizes of PVC and EMT also come in twenty foot lengths (20'), however they may be difficult to find in stock.  Start by calling local electrical supply companies in your area.  Flexible conduit comes in varying lengths depending on the size.  Smaller sizes can be up to 100' while the larger sizes may only be available in lengths as short as 25'.  Many supply houses will cut flexible conduit to order so there is no need to buy a full coil.
10' (Ten feet) of conduit =  120" (Inches)
10' (Ten feet) of conduit = 3.333333333 Yards
10' (Ten feet) of conduit = 3048 Millimeters
10' (Ten feet) of conduit = 304.8 Centimeters
10' (Ten feet) of conduit = 30.48 Decimeters
10' (Ten feet) of conduit = 3.048 Meters
Hole Sizes Needed to Terminate Conduit
For 1/2" conduit, drill using a 7/8" hole saw   For 2 1/2" conduit, drill using a 3" hole saw   
For 3/4" conduit, drill using a 1 1/8" hole saw For 3" conduit, drill using a 3 5/8" hole saw   
For 1" conduit, drill using a 1 3/8" hole saw    For 3 1/2" conduit, drill using a 4 1/8" hole saw
For 1 1/4" conduit, drill using a 1 3/4" hole saw For 4" conduit, drill using a 4 1/2" hole saw   
For 1 1/2" conduit, drill using a 1 7/8" hole saw    For 5" conduit, use a 5 5/8" Knockout Punch
For 2" conduit, drill using a 2 1/2" hole saw    For 6" conduit, use a 6 3/8" Knockout Punch
 
 
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Updated April 10, 2018

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