Thread type: M conical - Metric conical thread acc. to DIN 158-1

The thread presented in the table for the tapered M thread is a thread that is used for self-sealing connections. The specifications in the M tapered thread table correspond to the DIN 158-1 standard. This standard comprises a metric tapered external thread with an associated cylindrical internal thread, which must always be used in combination with each other. The cylindrical internal thread corresponds to the metric ISO thread. Due to the geometry of the thread shown in the M tapered thread table, the combination with a cylindrical internal thread creates a metal-to-metal sealing connection. With a small diameter, a good seal can be achieved for media such as oil, gas or liquids. The larger the nominal diameter according to the M tapered thread table, the more the tightness decreases and you should use an additional sealant. Specific areas of application for the tapered M thread according to the table are, for example, screw plugs, screw-in sockets or grease nipples.

The thread designation shown in the M tapered thread table is made up of the abbreviation M, followed by the nominal diameter and the pitch. The thread designation is often followed by the abbreviation "keg" outside the M tapered thread table to make it easier to distinguish it from the metric ISO thread. According to the DIN standard, a standard version and a short version are defined for the M tapered thread table. If the short version is used, the suffix "short" is also added to the thread designation. The correct designation for such an entry from the M tapered thread table is then: M 30 x 2 taper short.

The tapered metric thread according to DIN 158-1 has a flank angle of 60° and is characterized by a taper with a ratio of 1:16. In other words, the angle by which the taper is defined is 1°47'. In our thread table for the M tapered thread, you will find the outer diameter and the pitch in mm. We have also converted these two values for you, the outside diameter in inches and the pitch in threads per inch.

 outside-Ø in mmPitch P
in mm
in Zoll
Threads per Inch (TPI)
M 6 x 1.061,00,23625,400
M 8 x 1.081,00,31525,400
M 10 x 1.0101,00,39425,400
M 12 x 1.5121,50,47216,933
M 14 x 1.5141,50,55116,933
M 16 x 1.5161,50,63016,933
M 18 x 1.5181,50,70916,933
M 20 x 1.5201,50,78716,933
M 22 x 1.5221,50,86616,933
M 24 x 1.5241,50,94516,933

According to DIN 158-1, June 1997, only the external thread is conical during the internal thread is required cylindrical. Acc. to the old standard DIN 158, June 1954 internal and external threads are tapered. In practice, the tapered internal thread is still frequently used by the old standard.
For the metric conical external threads the variants are defined as generally and short version which are paired with a cylindrical internal thread (ISO metric threads) .
The Metric conical threads are used for self-sealing compounds, such as those occur at screw plugs, screw-and grease nipples.

Cross section of a metric tapered thread