Thread data sheet

Basic Thread Dimensions

Property mm Inch
Nominal Diameter 20 0.7874
Pitch (Distance) 2 0.0787
Pitch Diameter 18.701 0.7363
Minor Diameter 17.835 0.7022
Thread Height 1.083 0.0426
Addendum 0.65 0.0256
Crest (External)
Root (Internal)		 0.25 0.0098
Tap Drill Size
(75% depth)		 18.05 0.711
Lead Angle
(Single Start)		 1.95°
Thread Family Metric Fine Pitch (MF)
Relevant Standards ISO 68-1, ISO 9651-1, ISO 965-2, ISO 261,DIN 13
Equivalent InchThread13/16 - 12 12-UN

For more threading data scroll down, or use the Thread Calculator

Choose the Threading Data you want to explore

Unified Inch Thread Classes

Tolerance Classes

Thread Milling CNC program

Thread Milling Gcode

Turning Gcode

Over Wire

Tap Drill Size

Unified Inch Thread Classes

Tolerance Classes

Thread Milling Gcode

Turning Gcode

Over Wire

Tap Drill Size

M20 X 2Possible Thread Classes

External Threads

4g, 4h, 6e, 6g, 6h, 8e, 8g, 5g4g, 5h4h, 5g6g, 7g6g, 7h6h, 7e6e, 9e8e, 9g8g

Metric ISO External Thread - Tolerance sketch

Internal Threads

4H, 5H, 5G, 6H, 6G, 7H, 7G, 8G

Metric ISO Internal Thread - Tolerance sketch

M20 X 2 4g (External)

* Permisable values for thread Class 4g

# Description Value (mm) Value (Inch)
es Allowance 0.038 (Ref) 0.0015 (Ref)
d Major Diameter 19.782 - 19.962 0.7788 - 0.7859
d2 Pitch Diameter 18.563 - 18.663 0.7308 - 0.7348
R Root Radius 0.25 (Min) 0.0098 (Min)
C Root Truncation 0.25 - 0.44 0.0098 - 0.0173
LE Normal Length of Engagement 8 - 24 0.315 - 0.9449

* Back to Thread Class Selection

M20 X 2 4h (External)

* Permisable values for thread Class 4h

# Description Value (mm) Value (Inch)
es Allowance 0 (Ref) 0 (Ref)
d Major Diameter 19.82 - 20 0.7803 - 0.7874
d2 Pitch Diameter 18.601 - 18.701 0.7323 - 0.7363
R Root Radius 0.25 (Min) 0.0098 (Min)
C Root Truncation 0.25 - 0.44 0.0098 - 0.0173
LE Normal Length of Engagement 8 - 24 0.315 - 0.9449

* Back to Thread Class Selection

M20 X 2 6e (External)

* Permisable values for thread Class 6e

# Description Value (mm) Value (Inch)
es Allowance 0.071 (Ref) 0.0028 (Ref)
d Major Diameter 19.649 - 19.929 0.7736 - 0.7846
d2 Pitch Diameter 18.47 - 18.63 0.7272 - 0.7335
R Root Radius 0.25 (Min) 0.0098 (Min)
C Root Truncation 0.25 - 0.485 0.0098 - 0.0191
LE Normal Length of Engagement 8 - 24 0.315 - 0.9449

* Back to Thread Class Selection

M20 X 2 6g (External)

* Permisable values for thread Class 6g

# Description Value (mm) Value (Inch)
es Allowance 0.038 (Ref) 0.0015 (Ref)
d Major Diameter 19.682 - 19.962 0.7749 - 0.7859
d2 Pitch Diameter 18.503 - 18.663 0.7285 - 0.7348
R Root Radius 0.25 (Min) 0.0098 (Min)
C Root Truncation 0.25 - 0.485 0.0098 - 0.0191
LE Normal Length of Engagement 8 - 24 0.315 - 0.9449

* Back to Thread Class Selection

M20 X 2 6h (External)

* Permisable values for thread Class 6h

# Description Value (mm) Value (Inch)
es Allowance 0 (Ref) 0 (Ref)
d Major Diameter 19.72 - 20 0.7764 - 0.7874
d2 Pitch Diameter 18.541 - 18.701 0.73 - 0.7363
R Root Radius 0.25 (Min) 0.0098 (Min)
C Root Truncation 0.25 - 0.485 0.0098 - 0.0191
LE Normal Length of Engagement 8 - 24 0.315 - 0.9449

* Back to Thread Class Selection

M20 X 2 8e (External)

* Permisable values for thread Class 8e

# Description Value (mm) Value (Inch)
es Allowance 0.071 (Ref) 0.0028 (Ref)
d Major Diameter 19.479 - 19.929 0.7669 - 0.7846
d2 Pitch Diameter 18.38 - 18.63 0.7236 - 0.7335
R Root Radius 0.25 (Min) 0.0098 (Min)
C Root Truncation 0.25 - 0.545 0.0098 - 0.0215
LE Normal Length of Engagement 8 - 24 0.315 - 0.9449

* Back to Thread Class Selection

M20 X 2 8g (External)

* Permisable values for thread Class 8g

# Description Value (mm) Value (Inch)
es Allowance 0.038 (Ref) 0.0015 (Ref)
d Major Diameter 19.512 - 19.962 0.7682 - 0.7859
d2 Pitch Diameter 18.413 - 18.663 0.7249 - 0.7348
R Root Radius 0.25 (Min) 0.0098 (Min)
C Root Truncation 0.25 - 0.545 0.0098 - 0.0215
LE Normal Length of Engagement 8 - 24 0.315 - 0.9449

* Back to Thread Class Selection

M20 X 2 5g4g (External)

* Permisable values for thread Class 5g4g

# Description Value (mm) Value (Inch)
es Allowance 0.038 (Ref) 0.0015 (Ref)
d Major Diameter 19.782 - 19.962 0.7788 - 0.7859
d2 Pitch Diameter 18.538 - 18.663 0.7298 - 0.7348
R Root Radius 0.25 (Min) 0.0098 (Min)
C Root Truncation 0.25 - 0.46 0.0098 - 0.0181
LE Normal Length of Engagement 8 - 24 0.315 - 0.9449

* Back to Thread Class Selection

M20 X 2 5h4h (External)

* Permisable values for thread Class 5h4h

# Description Value (mm) Value (Inch)
es Allowance 0 (Ref) 0 (Ref)
d Major Diameter 19.82 - 20 0.7803 - 0.7874
d2 Pitch Diameter 18.576 - 18.701 0.7313 - 0.7363
R Root Radius 0.25 (Min) 0.0098 (Min)
C Root Truncation 0.25 - 0.46 0.0098 - 0.0181
LE Normal Length of Engagement 8 - 24 0.315 - 0.9449

* Back to Thread Class Selection

M20 X 2 5g6g (External)

* Permisable values for thread Class 5g6g

# Description Value (mm) Value (Inch)
es Allowance 0.038 (Ref) 0.0015 (Ref)
d Major Diameter 19.682 - 19.962 0.7749 - 0.7859
d2 Pitch Diameter 18.538 - 18.663 0.7298 - 0.7348
R Root Radius 0.25 (Min) 0.0098 (Min)
C Root Truncation 0.25 - 0.46 0.0098 - 0.0181
LE Normal Length of Engagement 8 - 24 0.315 - 0.9449

* Back to Thread Class Selection

M20 X 2 7g6g (External)

* Permisable values for thread Class 7g6g

# Description Value (mm) Value (Inch)
es Allowance 0.038 (Ref) 0.0015 (Ref)
d Major Diameter 19.682 - 19.962 0.7749 - 0.7859
d2 Pitch Diameter 18.463 - 18.663 0.7269 - 0.7348
R Root Radius 0.25 (Min) 0.0098 (Min)
C Root Truncation 0.25 - 0.513 0.0098 - 0.0202
LE Normal Length of Engagement 8 - 24 0.315 - 0.9449

* Back to Thread Class Selection

M20 X 2 7h6h (External)

* Permisable values for thread Class 7h6h

# Description Value (mm) Value (Inch)
es Allowance 0 (Ref) 0 (Ref)
d Major Diameter 19.72 - 20 0.7764 - 0.7874
d2 Pitch Diameter 18.501 - 18.701 0.7284 - 0.7363
R Root Radius 0.25 (Min) 0.0098 (Min)
C Root Truncation 0.25 - 0.513 0.0098 - 0.0202
LE Normal Length of Engagement 8 - 24 0.315 - 0.9449

* Back to Thread Class Selection

M20 X 2 7e6e (External)

* Permisable values for thread Class 7e6e

# Description Value (mm) Value (Inch)
es Allowance 0.071 (Ref) 0.0028 (Ref)
d Major Diameter 19.649 - 19.929 0.7736 - 0.7846
d2 Pitch Diameter 18.43 - 18.63 0.7256 - 0.7335
R Root Radius 0.25 (Min) 0.0098 (Min)
C Root Truncation 0.25 - 0.513 0.0098 - 0.0202
LE Normal Length of Engagement 8 - 24 0.315 - 0.9449

* Back to Thread Class Selection

M20 X 2 9e8e (External)

* Permisable values for thread Class 9e8e

# Description Value (mm) Value (Inch)
es Allowance 0.071 (Ref) 0.0028 (Ref)
d Major Diameter 19.479 - 19.929 0.7669 - 0.7846
d2 Pitch Diameter 18.315 - 18.63 0.7211 - 0.7335
R Root Radius 0.25 (Min) 0.0098 (Min)
C Root Truncation 0.25 - 0.584 0.0098 - 0.023
LE Normal Length of Engagement 8 - 24 0.315 - 0.9449

* Back to Thread Class Selection

M20 X 2 9g8g (External)

* Permisable values for thread Class 9g8g

# Description Value (mm) Value (Inch)
es Allowance 0.038 (Ref) 0.0015 (Ref)
d Major Diameter 19.512 - 19.962 0.7682 - 0.7859
d2 Pitch Diameter 18.348 - 18.663 0.7224 - 0.7348
R Root Radius 0.25 (Min) 0.0098 (Min)
C Root Truncation 0.25 - 0.584 0.0098 - 0.023
LE Normal Length of Engagement 8 - 24 0.315 - 0.9449

* Back to Thread Class Selection

M20 X 2 4H (Internal)

* Permisable values for thread Class 4H

# Description Value (mm) VValue (Inch)
EL Allowance 0 (Ref) 0 (Ref)
D1 Minor Diameter 17.835 - 18.071 0.7022 - 0.7115
D2 Pitch Diameter 18.701 - 18.833 0.7363 - 0.7415
D Major Diameter 20 (Min) 0.7874 (Min)
LE Normal Length of Engagement 8 - 24 0.315 - 0.9449

* Back to Thread Class Selection

M20 X 2 5H (Internal)

* Permisable values for thread Class 5H

# Description Value (mm) VValue (Inch)
EL Allowance 0 (Ref) 0 (Ref)
D1 Minor Diameter 17.835 - 18.135 0.7022 - 0.714
D2 Pitch Diameter 18.701 - 18.871 0.7363 - 0.743
D Major Diameter 20 (Min) 0.7874 (Min)
LE Normal Length of Engagement 8 - 24 0.315 - 0.9449

* Back to Thread Class Selection

M20 X 2 5G (Internal)

* Permisable values for thread Class 5G

# Description Value (mm) VValue (Inch)
EL Allowance 0.038 (Ref) 0.0015 (Ref)
D1 Minor Diameter 17.873 - 18.173 0.7037 - 0.7155
D2 Pitch Diameter 18.739 - 18.909 0.7378 - 0.7444
D Major Diameter 20 (Min) 0.7874 (Min)
LE Normal Length of Engagement 8 - 24 0.315 - 0.9449

* Back to Thread Class Selection

M20 X 2 6H (Internal)

* Permisable values for thread Class 6H

# Description Value (mm) VValue (Inch)
EL Allowance 0 (Ref) 0 (Ref)
D1 Minor Diameter 17.835 - 18.21 0.7022 - 0.7169
D2 Pitch Diameter 18.701 - 18.913 0.7363 - 0.7446
D Major Diameter 20 (Min) 0.7874 (Min)
LE Normal Length of Engagement 8 - 24 0.315 - 0.9449

* Back to Thread Class Selection

M20 X 2 6G (Internal)

* Permisable values for thread Class 6G

# Description Value (mm) VValue (Inch)
EL Allowance 0.038 (Ref) 0.0015 (Ref)
D1 Minor Diameter 17.873 - 18.248 0.7037 - 0.7184
D2 Pitch Diameter 18.739 - 18.951 0.7378 - 0.7461
D Major Diameter 20 (Min) 0.7874 (Min)
LE Normal Length of Engagement 8 - 24 0.315 - 0.9449

* Back to Thread Class Selection

M20 X 2 7H (Internal)

* Permisable values for thread Class 7H

# Description Value (mm) VValue (Inch)
EL Allowance 0 (Ref) 0 (Ref)
D1 Minor Diameter 17.835 - 18.31 0.7022 - 0.7209
D2 Pitch Diameter 18.701 - 18.966 0.7363 - 0.7467
D Major Diameter 20 (Min) 0.7874 (Min)
LE Normal Length of Engagement 8 - 24 0.315 - 0.9449

* Back to Thread Class Selection

M20 X 2 7G (Internal)

* Permisable values for thread Class 7G

# Description Value (mm) VValue (Inch)
EL Allowance 0.038 (Ref) 0.0015 (Ref)
D1 Minor Diameter 17.873 - 18.348 0.7037 - 0.7224
D2 Pitch Diameter 18.739 - 19.004 0.7378 - 0.7482
D Major Diameter 20 (Min) 0.7874 (Min)
LE Normal Length of Engagement 8 - 24 0.315 - 0.9449

* Back to Thread Class Selection

M20 X 2 8G (Internal)

* Permisable values for thread Class 8G

# Description Value (mm) VValue (Inch)
EL Allowance 0.038 (Ref) 0.0015 (Ref)
D1 Minor Diameter 17.873 - 18.473 0.7037 - 0.7273
D2 Pitch Diameter 18.739 - 19.074 0.7378 - 0.7509
D Major Diameter 20 (Min) 0.7874 (Min)
LE Normal Length of Engagement 8 - 24 0.315 - 0.9449

* Back to Thread Class Selection

Tap Drill Sizes for M20 X 2

  • If not specified, assume a thread depth of 75%.
  • You can learn more about thread depth in tapping here.
  • To get the tap drill size in other depths, use our Tap Drill Size Calculator .
Thread Depth Tap Drill Size (Inch) Tap Drill Size (mm)
55% 0.731 18.57
60% 0.726 18.44
65% 0.721 18.31
70% 0.716 18.18
75% 0.711 18.05
80% 0.706 17.92
85% 0.700 17.79

Over Wire Measurements for M20 X 2


* OverWire is a measuring method to obatin the pitch diameter of threads. It is mostly used when a manufacturer does not have a Go/Nogo gauge for a thread. You can learn more about it here

mm Inch
Permissible Wire Diameter Range 1.01 - 2.021 0.0398 - 0.0796
Ideal Wire Diameter 1.155 0.0455
Possible Wires
From Standard Sets		 * 1.01
* 1.155
* 1.443
* 1.732
* 2.021
 * 0.0642
* 0.0722
* 0.077

Once you know your wire diameter, you need to find out what is the premissable Measurement for your pitch diameter (Depending on the class). Use our Over Wire Calculator to find out!

CNC Gcode Program for Turning of M20 X 2

The below sample Gcode is configured for:

  • Fanuc Controller
  • External RH Thread
  • Right hand tool, machining towards the chuck
  • Flank Infeed method with contant volume
  • Flank Infeed method with contant volume
  • Cutting conditions for steel
  • Default number of passes

You can configure all the above parameters and much more in our Thread Turning Gcode Generator 


%
O0100
(MACHINING DOCTOR - THREADING CNC PROGRAM)
(CONTROLER - FANUC A)
(THREAD - D=20 MM, P=2 MM, L=20 MM)
(APPLICATION - EXTERNAL TURNING, TOWARDS CHUCK, RH TOOL, RH THREAD)
(FEED - 10 PASSES, FLANK, CONSTANT VOLUME)
(FINISH PASS - 0.032 MM)
(WITH CHAMFER -  NO)
G28 U0 W0
T0101 G99 G97 S1592 M03
G00 Z6.0
X 24.8 M08
G76 P010060 Q32 R0.032
G76 X17.546 Z-20.0 P1227 Q378 F2.0 R0.00 
G28 U0 W0
M09
M30
%

CNC Gcode Program for Thread Milling of M20 X 2

The below sample Gcode is configured for:

  • Fanuc Controller
  • Internal RH Thread
  • Climb Milling
  • Cutter diameter: 70% of the thread diameter
  • Single tooth Thread Mill cutter
  • Cutting conditions for steel
  • One radial pass

You can configure all the above parameters and much more in our Thread Milling Gcode Generator 


%
O101
(WWW.MACHININGDOCTOR.COM - THREADMILLING PROGRAM)
(CONTROLER - FANUC)
(THREAD - D=20 MM, P=2 MM, L=20 MM)
(APPLICATION - INTERNAL, RH THREAD, CLIMB MILLING)
(CUTTER - D=10 [SINGLE TOOTH])
N1 M06 T1
G54
G90 G40 G17 G94 G21
G00 X0 Y0 S3183 M03
G43 H1 Z20.0 M08
(M-CODE "THROUGH COOLANT ON")
(PASS 1 / 1)
G90 G01 Z-20.25 F2000
G91 G01 G41 D1 X2.5 Y-2.5 F477
G03 X2.5 Y2.5 Z0.25 I0 J2.5 F120
G03 Z2.0 I-5.0 J0 F239
G03 Z2.0 I-5.0 J0
G03 Z2.0 I-5.0 J0
G03 Z2.0 I-5.0 J0
G03 Z2.0 I-5.0 J0
G03 Z2.0 I-5.0 J0
G03 Z2.0 I-5.0 J0
G03 Z2.0 I-5.0 J0
G03 Z2.0 I-5.0 J0
G03 Z2.0 I-5.0 J0
G03 X-2.5 Y2.5 Z0.25 I-2.5 J0
G01 G40 X-2.5 Y-2.5 F2000
G90 G00 Z20.0
M30
(PLEASE NOTE THIS GCODE HAS NOT BEEN TESTED ON YOUR MACHINE AND SETUP. WE CANNOT GUARANTEE ITS ACCURACY OR COMPATIBILITY. NOTE THAT YOU ARE USING IT AT YOUR OWN RISK, AND WE SHALL NOT BE HELD LIABLE FOR ANY DAMAGES OR LOSSES ARISING FROM THE USE OF THIS PROGRAM.)
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