M4 - Basic Thread Dimensions

Property mm Inch
Nominal Diameter 4 0.1575
Pitch (Distance) 0.7 0.0276
Pitch Diameter 3.545 0.1396
Minor Diameter 3.242 0.1276
Thread Height 0.379 0.0149
Addendum 0.227 0.0089
Crest (External)
Root (Internal)		 0.088 0.0035
Tap Drill Size
(75% depth)		 3.32 0.131
Lead Angle
(Single Start)		 3.6°
Thread Family Metric Coarse Pitch (MC)
Relevant Standards ISO 68-1, ISO 9651-1, ISO 965-2, ISO 261,DIN 13
Equivalent Inch Thread#8 - 36 UNF

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

Table of Content

M4 Possible Thread Classes

External Threads

Choose tolerance class: 4g, 4h, 6e, 6g, 6h, 5g4g, 5h4h, 5g6g, 7g6g, 7h6h, 7e6e

Metric ISO External Thread - Tolerance sketch

Internal Threads

Choose tolerance class: 4H, 5H, 5G, 6H, 6G, 7H, 7G

Metric ISO Internal Thread - Tolerance sketch

M4 4g (External)

* Permisable values for thread Class 4g

# Description Value (mm) Value (Inch)
es Allowance 0.022 (Ref) 0.0009 (Ref)
d Major Diameter 3.888 - 3.978 0.1531 - 0.1566
d2 Pitch Diameter 3.467 - 3.523 0.1365 - 0.1387
R Root Radius 0.088 (Min) 0.0035 (Min)
C Root Truncation 0.088 - 0.17 0.0035 - 0.0067
LE Normal Length of Engagement 2 - 6 0.0787 - 0.2362

* Back to Thread Class Selection

M4 4h (External)

* Permisable values for thread Class 4h

# Description Value (mm) Value (Inch)
es Allowance 0 (Ref) 0 (Ref)
d Major Diameter 3.91 - 4 0.1539 - 0.1575
d2 Pitch Diameter 3.489 - 3.545 0.1374 - 0.1396
R Root Radius 0.088 (Min) 0.0035 (Min)
C Root Truncation 0.088 - 0.17 0.0035 - 0.0067
LE Normal Length of Engagement 2 - 6 0.0787 - 0.2362

* Back to Thread Class Selection

M4 6e (External)

* Permisable values for thread Class 6e

# Description Value (mm) Value (Inch)
es Allowance 0.056 (Ref) 0.0022 (Ref)
d Major Diameter 3.804 - 3.944 0.1498 - 0.1553
d2 Pitch Diameter 3.399 - 3.489 0.1338 - 0.1374
R Root Radius 0.088 (Min) 0.0035 (Min)
C Root Truncation 0.088 - 0.192 0.0035 - 0.0076
LE Normal Length of Engagement 2 - 6 0.0787 - 0.2362

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M4 6g (External)

* Permisable values for thread Class 6g

# Description Value (mm) Value (Inch)
es Allowance 0.022 (Ref) 0.0009 (Ref)
d Major Diameter 3.838 - 3.978 0.1511 - 0.1566
d2 Pitch Diameter 3.433 - 3.523 0.1352 - 0.1387
R Root Radius 0.088 (Min) 0.0035 (Min)
C Root Truncation 0.088 - 0.192 0.0035 - 0.0076
LE Normal Length of Engagement 2 - 6 0.0787 - 0.2362

* Back to Thread Class Selection

M4 6h (External)

* Permisable values for thread Class 6h

# Description Value (mm) Value (Inch)
es Allowance 0 (Ref) 0 (Ref)
d Major Diameter 3.86 - 4 0.152 - 0.1575
d2 Pitch Diameter 3.455 - 3.545 0.136 - 0.1396
R Root Radius 0.088 (Min) 0.0035 (Min)
C Root Truncation 0.088 - 0.192 0.0035 - 0.0076
LE Normal Length of Engagement 2 - 6 0.0787 - 0.2362

* Back to Thread Class Selection

M4 5g4g (External)

* Permisable values for thread Class 5g4g

# Description Value (mm) Value (Inch)
es Allowance 0.022 (Ref) 0.0009 (Ref)
d Major Diameter 3.888 - 3.978 0.1531 - 0.1566
d2 Pitch Diameter 3.452 - 3.523 0.1359 - 0.1387
R Root Radius 0.088 (Min) 0.0035 (Min)
C Root Truncation 0.088 - 0.18 0.0035 - 0.0071
LE Normal Length of Engagement 2 - 6 0.0787 - 0.2362

* Back to Thread Class Selection

M4 5h4h (External)

* Permisable values for thread Class 5h4h

# Description Value (mm) Value (Inch)
es Allowance 0 (Ref) 0 (Ref)
d Major Diameter 3.91 - 4 0.1539 - 0.1575
d2 Pitch Diameter 3.474 - 3.545 0.1368 - 0.1396
R Root Radius 0.088 (Min) 0.0035 (Min)
C Root Truncation 0.088 - 0.18 0.0035 - 0.0071
LE Normal Length of Engagement 2 - 6 0.0787 - 0.2362

* Back to Thread Class Selection

M4 5g6g (External)

* Permisable values for thread Class 5g6g

# Description Value (mm) Value (Inch)
es Allowance 0.022 (Ref) 0.0009 (Ref)
d Major Diameter 3.838 - 3.978 0.1511 - 0.1566
d2 Pitch Diameter 3.452 - 3.523 0.1359 - 0.1387
R Root Radius 0.088 (Min) 0.0035 (Min)
C Root Truncation 0.088 - 0.18 0.0035 - 0.0071
LE Normal Length of Engagement 2 - 6 0.0787 - 0.2362

* Back to Thread Class Selection

M4 7g6g (External)

* Permisable values for thread Class 7g6g

# Description Value (mm) Value (Inch)
es Allowance 0.022 (Ref) 0.0009 (Ref)
d Major Diameter 3.838 - 3.978 0.1511 - 0.1566
d2 Pitch Diameter 3.411 - 3.523 0.1343 - 0.1387
R Root Radius 0.088 (Min) 0.0035 (Min)
C Root Truncation 0.088 - 0.205 0.0035 - 0.0081
LE Normal Length of Engagement 2 - 6 0.0787 - 0.2362

* Back to Thread Class Selection

M4 7h6h (External)

* Permisable values for thread Class 7h6h

# Description Value (mm) Value (Inch)
es Allowance 0 (Ref) 0 (Ref)
d Major Diameter 3.86 - 4 0.152 - 0.1575
d2 Pitch Diameter 3.433 - 3.545 0.1352 - 0.1396
R Root Radius 0.088 (Min) 0.0035 (Min)
C Root Truncation 0.088 - 0.205 0.0035 - 0.0081
LE Normal Length of Engagement 2 - 6 0.0787 - 0.2362

* Back to Thread Class Selection

M4 7e6e (External)

* Permisable values for thread Class 7e6e

# Description Value (mm) Value (Inch)
es Allowance 0.056 (Ref) 0.0022 (Ref)
d Major Diameter 3.804 - 3.944 0.1498 - 0.1553
d2 Pitch Diameter 3.377 - 3.489 0.133 - 0.1374
R Root Radius 0.088 (Min) 0.0035 (Min)
C Root Truncation 0.088 - 0.205 0.0035 - 0.0081
LE Normal Length of Engagement 2 - 6 0.0787 - 0.2362

* Back to Thread Class Selection

M4 4H (Internal)

* Permisable values for thread Class 4H

# Description Value (mm) Value (Inch)
EL Allowance 0 (Ref) 0 (Ref)
D1 Minor Diameter 3.242 - 3.354 0.1276 - 0.132
D2 Pitch Diameter 3.545 - 3.62 0.1396 - 0.1425
D Major Diameter 4 (Min) 0.1575 (Min)
LE Normal Length of Engagement 2 - 6 0.0787 - 0.2362

* Back to Thread Class Selection

M4 5H (Internal)

* Permisable values for thread Class 5H

# Description Value (mm) Value (Inch)
EL Allowance 0 (Ref) 0 (Ref)
D1 Minor Diameter 3.242 - 3.382 0.1276 - 0.1331
D2 Pitch Diameter 3.545 - 3.64 0.1396 - 0.1433
D Major Diameter 4 (Min) 0.1575 (Min)
LE Normal Length of Engagement 2 - 6 0.0787 - 0.2362

* Back to Thread Class Selection

M4 5G (Internal)

* Permisable values for thread Class 5G

# Description Value (mm) Value (Inch)
EL Allowance 0.022 (Ref) 0.0009 (Ref)
D1 Minor Diameter 3.264 - 3.404 0.1285 - 0.134
D2 Pitch Diameter 3.567 - 3.662 0.1404 - 0.1442
D Major Diameter 4 (Min) 0.1575 (Min)
LE Normal Length of Engagement 2 - 6 0.0787 - 0.2362

* Back to Thread Class Selection

M4 6H (Internal)

* Permisable values for thread Class 6H

# Description Value (mm) Value (Inch)
EL Allowance 0 (Ref) 0 (Ref)
D1 Minor Diameter 3.242 - 3.422 0.1276 - 0.1347
D2 Pitch Diameter 3.545 - 3.663 0.1396 - 0.1442
D Major Diameter 4 (Min) 0.1575 (Min)
LE Normal Length of Engagement 2 - 6 0.0787 - 0.2362

* Back to Thread Class Selection

M4 6G (Internal)

* Permisable values for thread Class 6G

# Description Value (mm) Value (Inch)
EL Allowance 0.022 (Ref) 0.0009 (Ref)
D1 Minor Diameter 3.264 - 3.444 0.1285 - 0.1356
D2 Pitch Diameter 3.567 - 3.685 0.1404 - 0.1451
D Major Diameter 4 (Min) 0.1575 (Min)
LE Normal Length of Engagement 2 - 6 0.0787 - 0.2362

* Back to Thread Class Selection

M4 7H (Internal)

* Permisable values for thread Class 7H

# Description Value (mm) Value (Inch)
EL Allowance 0 (Ref) 0 (Ref)
D1 Minor Diameter 3.242 - 3.466 0.1276 - 0.1365
D2 Pitch Diameter 3.545 - 3.695 0.1396 - 0.1455
D Major Diameter 4 (Min) 0.1575 (Min)
LE Normal Length of Engagement 2 - 6 0.0787 - 0.2362

* Back to Thread Class Selection

M4 7G (Internal)

* Permisable values for thread Class 7G

# Description Value (mm) Value (Inch)
EL Allowance 0.022 (Ref) 0.0009 (Ref)
D1 Minor Diameter 3.264 - 3.488 0.1285 - 0.1373
D2 Pitch Diameter 3.567 - 3.717 0.1404 - 0.1463
D Major Diameter 4 (Min) 0.1575 (Min)
LE Normal Length of Engagement 2 - 6 0.0787 - 0.2362

* Back to Thread Class Selection

Tap Drill Sizes for M4

  • 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% 0.138 3.50
60% 0.136 3.45
65% 0.134 3.41
70% 0.132 3.36
75% 0.131 3.32
80% 0.129 3.27
85% 0.127 3.23

Over Wire Measurements for M4


* 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 0.354 - 0.707 0.0139 - 0.0278
Ideal Wire Diameter 0.404 0.0159
Possible Wires
From Standard Sets		 * 0.404
* 0.433
* 0.462
* 0.52
* 0.577
 * 0.0144
* 0.016
* 0.018
* 0.0193
* 0.0206
* 0.0214
* 0.0222
* 0.0241
* 0.0262

Once you knoe 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!


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