Thread data sheet

Basic Thread Dimensions

Property mm Inch
Nominal Diameter 2.5 0.0984
Pitch (Distance) 0.45 0.0177
Pitch Diameter 2.208 0.0869
Minor Diameter 2.013 0.0793
Thread Height 0.244 0.0096
Addendum 0.146 0.0057
Crest (External)
Root (Internal)		 0.056 0.0022
Tap Drill Size
(75% depth)		 2.06 0.081
Lead Angle
(Single Start)		 3.71°
Thread Family Metric Coarse Pitch (MC)
Relevant Standards ISO 68-1, ISO 9651-1, ISO 965-2, ISO 261,DIN 13
Equivalent InchThread#3 - 56 UNF

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

M2.5Possible Thread Classes

External Threads

4g, 4h, 6g, 6h, 5g4g, 5h4h, 5g6g, 7g6g, 7h6h

Metric ISO External Thread - Tolerance sketch

Internal Threads

4H, 5H, 5G, 6H, 6G

Metric ISO Internal Thread - Tolerance sketch

M2.5 4g (External)

* Permisable values for thread Class 4g

# Description Value (mm) Value (Inch)
es Allowance 0.02 (Ref) 0.0008 (Ref)
d Major Diameter 2.417 - 2.48 0.0952 - 0.0976
d2 Pitch Diameter 2.143 - 2.188 0.0844 - 0.0861
R Root Radius 0.056 (Min) 0.0022 (Min)
C Root Truncation 0.056 - 0.115 0.0022 - 0.0045
LE Normal Length of Engagement 1.3 - 3.8 0.0512 - 0.1496

* Back to Thread Class Selection

M2.5 4h (External)

* Permisable values for thread Class 4h

# Description Value (mm) Value (Inch)
es Allowance 0 (Ref) 0 (Ref)
d Major Diameter 2.437 - 2.5 0.0959 - 0.0984
d2 Pitch Diameter 2.163 - 2.208 0.0852 - 0.0869
R Root Radius 0.056 (Min) 0.0022 (Min)
C Root Truncation 0.056 - 0.115 0.0022 - 0.0045
LE Normal Length of Engagement 1.3 - 3.8 0.0512 - 0.1496

* Back to Thread Class Selection

M2.5 6g (External)

* Permisable values for thread Class 6g

# Description Value (mm) Value (Inch)
es Allowance 0.02 (Ref) 0.0008 (Ref)
d Major Diameter 2.38 - 2.48 0.0937 - 0.0976
d2 Pitch Diameter 2.117 - 2.188 0.0833 - 0.0861
R Root Radius 0.056 (Min) 0.0022 (Min)
C Root Truncation 0.056 - 0.131 0.0022 - 0.0052
LE Normal Length of Engagement 1.3 - 3.8 0.0512 - 0.1496

* Back to Thread Class Selection

M2.5 6h (External)

* Permisable values for thread Class 6h

# Description Value (mm) Value (Inch)
es Allowance 0 (Ref) 0 (Ref)
d Major Diameter 2.4 - 2.5 0.0945 - 0.0984
d2 Pitch Diameter 2.137 - 2.208 0.0841 - 0.0869
R Root Radius 0.056 (Min) 0.0022 (Min)
C Root Truncation 0.056 - 0.131 0.0022 - 0.0052
LE Normal Length of Engagement 1.3 - 3.8 0.0512 - 0.1496

* Back to Thread Class Selection

M2.5 5g4g (External)

* Permisable values for thread Class 5g4g

# Description Value (mm) Value (Inch)
es Allowance 0.02 (Ref) 0.0008 (Ref)
d Major Diameter 2.417 - 2.48 0.0952 - 0.0976
d2 Pitch Diameter 2.132 - 2.188 0.0839 - 0.0861
R Root Radius 0.056 (Min) 0.0022 (Min)
C Root Truncation 0.056 - 0.122 0.0022 - 0.0048
LE Normal Length of Engagement 1.3 - 3.8 0.0512 - 0.1496

* Back to Thread Class Selection

M2.5 5h4h (External)

* Permisable values for thread Class 5h4h

# Description Value (mm) Value (Inch)
es Allowance 0 (Ref) 0 (Ref)
d Major Diameter 2.437 - 2.5 0.0959 - 0.0984
d2 Pitch Diameter 2.152 - 2.208 0.0847 - 0.0869
R Root Radius 0.056 (Min) 0.0022 (Min)
C Root Truncation 0.056 - 0.122 0.0022 - 0.0048
LE Normal Length of Engagement 1.3 - 3.8 0.0512 - 0.1496

* Back to Thread Class Selection

M2.5 5g6g (External)

* Permisable values for thread Class 5g6g

# Description Value (mm) Value (Inch)
es Allowance 0.02 (Ref) 0.0008 (Ref)
d Major Diameter 2.38 - 2.48 0.0937 - 0.0976
d2 Pitch Diameter 2.132 - 2.188 0.0839 - 0.0861
R Root Radius 0.056 (Min) 0.0022 (Min)
C Root Truncation 0.056 - 0.122 0.0022 - 0.0048
LE Normal Length of Engagement 1.3 - 3.8 0.0512 - 0.1496

* Back to Thread Class Selection

M2.5 7g6g (External)

* Permisable values for thread Class 7g6g

# Description Value (mm) Value (Inch)
es Allowance 0.02 (Ref) 0.0008 (Ref)
d Major Diameter 2.38 - 2.48 0.0937 - 0.0976
d2 Pitch Diameter 2.098 - 2.188 0.0826 - 0.0861
R Root Radius 0.056 (Min) 0.0022 (Min)
C Root Truncation 0.056 - 0.142 0.0022 - 0.0056
LE Normal Length of Engagement 1.3 - 3.8 0.0512 - 0.1496

* Back to Thread Class Selection

M2.5 7h6h (External)

* Permisable values for thread Class 7h6h

# Description Value (mm) Value (Inch)
es Allowance 0 (Ref) 0 (Ref)
d Major Diameter 2.4 - 2.5 0.0945 - 0.0984
d2 Pitch Diameter 2.118 - 2.208 0.0834 - 0.0869
R Root Radius 0.056 (Min) 0.0022 (Min)
C Root Truncation 0.056 - 0.142 0.0022 - 0.0056
LE Normal Length of Engagement 1.3 - 3.8 0.0512 - 0.1496

* Back to Thread Class Selection

M2.5 4H (Internal)

* Permisable values for thread Class 4H

# Description Value (mm) VValue (Inch)
EL Allowance 0 (Ref) 0 (Ref)
D1 Minor Diameter 2.013 - 2.093 0.0793 - 0.0824
D2 Pitch Diameter 2.208 - 2.268 0.0869 - 0.0893
D Major Diameter 2.5 (Min) 0.0984 (Min)
LE Normal Length of Engagement 1.3 - 3.8 0.0512 - 0.1496

* Back to Thread Class Selection

M2.5 5H (Internal)

* Permisable values for thread Class 5H

# Description Value (mm) VValue (Inch)
EL Allowance 0 (Ref) 0 (Ref)
D1 Minor Diameter 2.013 - 2.113 0.0793 - 0.0832
D2 Pitch Diameter 2.208 - 2.283 0.0869 - 0.0899
D Major Diameter 2.5 (Min) 0.0984 (Min)
LE Normal Length of Engagement 1.3 - 3.8 0.0512 - 0.1496

* Back to Thread Class Selection

M2.5 5G (Internal)

* Permisable values for thread Class 5G

# Description Value (mm) VValue (Inch)
EL Allowance 0.02 (Ref) 0.0008 (Ref)
D1 Minor Diameter 2.033 - 2.133 0.08 - 0.084
D2 Pitch Diameter 2.228 - 2.303 0.0877 - 0.0907
D Major Diameter 2.5 (Min) 0.0984 (Min)
LE Normal Length of Engagement 1.3 - 3.8 0.0512 - 0.1496

* Back to Thread Class Selection

M2.5 6H (Internal)

* Permisable values for thread Class 6H

# Description Value (mm) VValue (Inch)
EL Allowance 0 (Ref) 0 (Ref)
D1 Minor Diameter 2.013 - 2.138 0.0793 - 0.0842
D2 Pitch Diameter 2.208 - 2.303 0.0869 - 0.0907
D Major Diameter 2.5 (Min) 0.0984 (Min)
LE Normal Length of Engagement 1.3 - 3.8 0.0512 - 0.1496

* Back to Thread Class Selection

M2.5 6G (Internal)

* Permisable values for thread Class 6G

# Description Value (mm) VValue (Inch)
EL Allowance 0.02 (Ref) 0.0008 (Ref)
D1 Minor Diameter 2.033 - 2.158 0.08 - 0.085
D2 Pitch Diameter 2.228 - 2.323 0.0877 - 0.0915
D Major Diameter 2.5 (Min) 0.0984 (Min)
LE Normal Length of Engagement 1.3 - 3.8 0.0512 - 0.1496

* Back to Thread Class Selection

Tap Drill Sizes for M2.5

  • 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% 0.086 2.18
60% 0.085 2.15
65% 0.083 2.12
70% 0.082 2.09
75% 0.081 2.06
80% 0.080 2.03
85% 0.079 2.00

Over Wire Measurements for M2.5


* 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 0.227 - 0.455 0.009 - 0.0179
Ideal Wire Diameter 0.26 0.0102
Possible Wires
From Standard Sets		 * 0.231
* 0.26
* 0.289
* 0.346
* 0.404
* 0.433
 * 0.009
* 0.0103
* 0.0116
* 0.012
* 0.0131
* 0.0144
* 0.016

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 M2.5

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=2.5 MM, P=0.45 MM, L=4.5 MM)
(APPLICATION - EXTERNAL TURNING, TOWARDS CHUCK, RH TOOL, RH THREAD)
(FEED - 4 PASSES, FLANK, CONSTANT VOLUME)
(FINISH PASS - 0.017 MM)
(WITH CHAMFER -  NO)
G28 U0 W0
T0101 G99 G97 S5000 M03
G00 Z5.0
X 4.5 M08
G76 P010060 Q17 R0.017
G76 X1.948 Z-4.5 P276 Q130 F0.45 R0.00 
G28 U0 W0
M09
M30
%

CNC Gcode Program for Thread Milling of M2.5

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=2.5 MM, P=0.45 MM, L=4.5 MM)
(APPLICATION - INTERNAL, RH THREAD, CLIMB MILLING)
(CUTTER - D=1.25 [SINGLE TOOTH])
N1 M06 T1
G54
G90 G40 G17 G94 G21
G00 X0 Y0 S10000 M03
G43 H1 Z20.0 M08
(M-CODE "THROUGH COOLANT ON")
(PASS 1 / 1)
G90 G01 Z-4.556 F2000
G91 G01 G41 D1 X0.313 Y-0.313 F1500
G03 X0.313 Y0.313 Z0.056 I0 J0.313 F375
G03 Z0.45 I-0.625 J0 F750
G03 Z0.45 I-0.625 J0
G03 Z0.45 I-0.625 J0
G03 Z0.45 I-0.625 J0
G03 Z0.45 I-0.625 J0
G03 Z0.45 I-0.625 J0
G03 Z0.45 I-0.625 J0
G03 Z0.45 I-0.625 J0
G03 Z0.45 I-0.625 J0
G03 Z0.45 I-0.625 J0
G03 X-0.313 Y0.313 Z0.056 I-0.313 J0
G01 G40 X-0.313 Y-0.313 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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