EXTERNAL METRIC THREAD DIMENSIONS CHART


Metric thread dimensions chart for external threads according to ASME B1.13M-2005 "Metric Screw Threads: M Profile" standard. Dimensions of major diameter, pitch diameter and minor diameter for M profile metric external threads are given in the chart. All dimensions are in millimeters.

External thread (or bolt thread) is a term to describe all external threads in ISO metric thread standards.

Threads produced to ASME B1.13M-2005 standard are fully interchangeable with threads that are based on ISO 68-1 basic profile and ISO 965-1 tolerance practices.

External Thread Tolerance Classes:

    - for normal tolerance — tolerance class 6g

    - for tighter tolerance — tolerance class 4g6g

    - for a no-allowance fit at maximum material, such as for a plated 6g — tolerance class 6h

Size limits for standard external thread tolerance classes 6g and 4g6g apply prior to coating. The external thread allowance may thus be used to accommodate the coating thickness on coated parts.

The designation of a screw thread gives the thread symbol, the nominal size, the pitch, and the thread tolerance class (Ex: M6 x 1 - 4g6g). In tolerance class designation, the pitch diameter tolerance is followed by major diameter tolerance. If the two class designations for the pitch diameter and major diameter are same, it is not necessary to repeat the symbols. (Ex: M6 x 1 - 6g)

External Thread M Profile With No Allowance



Metric Thread Calculator:

Thread Designation Tolerance Class Results
Thread Designation ---
Pitch, p ---
Tolerance Class ---
Major Diameter dmax  ---
dmin ---
Pitch Diameter d2max ---
d2min ---
Maximum Minor Diameter
(Flat Form)
d1max ---
Maximum Minor Diameter
(Rounded Form),
d3max ---
Minimum Minor Diameter
(Rounded Form)
d3min ---

 






Note-1: Maximum rounded form minor diameter is calculated with following formula. The rest of the dimensions are tabulated values from the ASME standard.
Maximum rounded form minor diameter = d3max =  d2max - (0.5H + 2rmin (1 − cos (60deg − arccos(1 − Td2/ 4rmin)))). Here, rmin is minimum root radius, Td2 is pitch diameter tolerance and H is height of sharp V-thread.

Metric Thread Chart:


External Metric Thread Chart — Limiting Dimensions for M Profile
Thread
Designation
Pitch, p Tolerance
Class
Major Dia.,
d
Pitch Dia.,
d2
Max.
Minor
Diameter
(Flat
Form)
d1
Min.
Minor
Diameter
(Rounded
Form)
d3
max. min. max. min.
M1.6 x 0.35 0.35 6g 1.581 1.496 1.354 1.291 1.202 1.075
M1.6 x 0.35 0.35 6h 1.600 1.515 1.373 1.310 1.221 1.094
M1.6 x 0.35 0.35 4g6g 1.581 1.496 1.354 1.314 1.202 1.098
M2 x 0.4 0.4 6g 1.981 1.886 1.721 1.654 1.548 1.408
M2 x 0.4 0.4 6h 2.000 1.905 1.740 1.673 1.567 1.427
M2 x 0.4 0.4 4g6g 1.981 1.886 1.721 1.679 1.548 1.433
M2.5 x 0.45 0.45 6g 2.480 2.380 2.188 2.117 1.993 1.840
M2.5 x 0.45 0.45 6h 2.500 2.400 2.208 2.137 2.013 1.860
M2.5 x 0.45 0.45 4g6g 2.480 2.380 2.188 2.143 1.993 1.866
M3 x 0.5 0.5 6g 2.980 2.874 2.655 2.580 2.438 2.272
M3 x 0.5 0.5 6h 3.000 2.894 2.675 2.600 2.458 2.292
M3 x 0.5 0.5 4g6g 2.980 2.874 2.655 2.607 2.438 2.299
M3.5 x 0.6 0.6 6g 3.479 3.354 3.089 3.004 2.829 2.634
M3.5 x 0.6 0.6 6h 3.500 3.375 3.110 3.025 2.850 2.655
M3.5 x  0.6 0.6 4g6g 3.479 3.354 3.089 3.036 2.829 2.666
M4 x 0.7 0.7 6g 3.978 3.838 3.523 3.433 3.220 3.002
M4 x 0.7 0.7 6h 4.000 3.860 3.545 3.455 3.242 3.024
M4 x 0.7 0.7 4g6g 3.978 3.838 3.523 3.467 3.220 3.036
M5 x 0.8 0.8 6g 4.976 4.826 4.456 4.361 4.110 3.868
M5 x 0.8 0.8 6h 5.000 4.850 4.480 4.385 4.134 3.892
M5 x 0.8 0.8 4g6g 4.976 4.826 4.456 4.396 4.110 3.903
M6 x 1 1 6g 5.974 5.794 5.324 5.212 4.891 4.596
M6 x 1 1 6h 6.000 5.820 5.350 5.238 4.917 4.622
M6 x 1 1 4g6g 5.974 5.794 5.324 5.253 4.891 4.637
M8 x 1.25 1.25 6g 7.972 7.760 7.160 7.042 6.619 6.272
M8 x 1.25 1.25 6h 8.000 7.788 7.188 7.070 6.647 6.300
M8 x 1.25 1.25 4g6g 7.972 7.760 7.160 7.085 6.619 6.315
M8 x 1 1 6g 7.974 7.794 7.324 7.212 6.891 6.596
M8 x 1 1 6h 8.000 7.820 7.350 7.238 6.917 6.622
M8 x 1 1 4g6g 7.974 7.794 7.324 7.253 6.891 6.637
M10 x 1.5 1.5 6g 9.968 9.732 8.994 8.862 8.344 7.938
M10 x 1.5 1.5 6h 10.000 9.764 9.026 8.894 8.376 7.970
M10 x 1.5 1.5 4g6g 9.968 9.732 8.994 8.909 8.344 7.985
M10 x 1.25 1.25 6g 9.972 9.760 9.160 9.042 8.619 8.272
M10 x 1.25 1.25 6h 10.000 9.788 9.188 9.070 8.647 8.300
M10 x 1.25 1.25 4g6g 9.972 9.760 9.160 9.085 8.619 8.315
M10 x 1 1 6g 9.974 9.794 9.324 9.212 8.891 8.596
M10 x 1 1 6h 10.000 9.820 9.350 9.238 8.917 8.622
M10 x 1 1 4g6g 9.974 9.794 9.324 9.253 8.891 8.637
M10 x 0.75 0.75 6g 9.978 9.838 9.491 9.391 9.166 8.929
M10 x 0.75 0.75 6h 10.000 9.860 9.513 9.413 9.188 8.951
M10 x 0.75 0.75 4g6g 9.978 9.838 9.491 9.428 9.166 8.966
M12 x 1.75 1.75 6g 11.966 11.701 10.829 10.679 10.071 9.601
M12 x 1.75 1.75 6h 12.000 11.735 10.863 10.713 10.105 9.635
M12 x 1.75 1.75 4g6g 11.966 11.701 10.829 10.734 10.071 9.656
M12 x 1.5 1.5 6g 11.968 11.732 10.994 10.854 10.344 9.930
M12 x 1.5 1.5 6h 12.000 11.764 11.026 10.886 10.376 9.962
M12 x 1.5 1.5 4g6g 11.968 11.732 10.994 10.904 10.344 9.980
M12 x 1.25 1.25 6g 11.972 11.760 11.160 11.028 10.619 10.258
M12 x 1.25 1.25 6h 12.000 11.788 11.188 11.056 10.647 10.286
M12 x 1.25 1.25 4g6g 11.972 11.760 11.160 11.075 10.619 10.305
M12 x 1 1 6g 11.974 11.794 11.324 11.206 10.891 10.590
M12 x 1 1 6h 12.000 11.820 11.350 11.232 10.917 10.616
M12 x 1 1 4g6g 11.974 11.794 11.324 11.249 10.891 10.633
M14 x 2 2 6g 13.962 13.682 12.663 12.503 11.797 11.271
M14 x 2 2 6h 14.000 13.720 12.701 12.541 11.835 11.309
M14 x 2 2 4g6g 13.962 13.682 12.663 12.563 11.797 11.331
M14 x 1.5 1.5 6g 13.968 13.732 12.994 12.854 12.344 11.930
M14 x 1.5 1.5 6h 14.000 13.764 13.026 12.886 12.376 11.962
M14 x 1.5 1.5 4g6g 13.968 13.732 12.994 12.904 12.344 11.980
M15 x 1 1 6g 14.974 14.794 14.324 14.206 13.891 13.590
M15 x 1 1 6h 15.000 14.820 14.350 14.232 13.917 13.616
M15 x 1 1 4g6g 14.974 14.794 14.324 14.249 13.891 13.633
M16 x 2 2 6g 15.962 15.682 14.663 14.503 13.797 13.271
M16 x 2 2 6h 16.000 15.720 14.701 14.541 13.835 13.309
M16 x 2 2 4g6g 15.962 15.682 14.663 14.563 13.797 13.331
M16 x 1.5 1.5 6g 15.968 15.732 14.994 14.854 14.344 13.930
M16 x 1.5 1.5 6h 16.000 15.764 15.026 14.886 14.376 13.962
M16 x 1.5 1.5 4g6g 15.968 15.732 14.994 14.904 14.344 13.980

Supplements:


Link Usage
ISO metric screw thread calculator ISO metric screw thread calculator based on ISO standards

Definitions:


Allowance: The difference between the maximum material size and the basic size.

Basic profile: The theoretical profile of a screw thread in an axial plane defined by theoretical dimensions and angles common to internal and external threads. The basic M thread profile for metric screw threads is shown below.

The basic profile for ISO general purpose metric screw threads
ISO metric screw thread basic profile according to ISO 68-1

Reference:
  • ASME B1.13M-2005 "Metric Screw Threads: M Profile"
  • Oberg, E. , Jones ,F.D. , Horton H.L. , Ryffel H.H., (2016) . Machinery's Handbook . 30th edition.  Industrial Press Inc.
  • Oberg, E. , Jones ,F.D. , Horton H.L. , Ryffel H.H., (2012) . Machinery's Handbook . 29th edition.  Industrial Press Inc.