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

I
nside
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
Not responsible for errors and omissions regarding the content of this page