ISO Metric Fine Thread DIN 13-2 to 13-11

The metric ISO fine thread is the corresponding fine thread to the metric standard thread. It differs from the latter by having a smaller pitch and a correspondingly narrower thread profile. As a fine thread, it has better self-locking and less thread depth than the standard thread. The metric ISO fine thread is therefore preferred over the standard thread, especially when there is limited space (e.g., in components with thin wall thickness) and in environments where frequent vibrations and shocks could cause a screw to loosen itself. The smaller pitch also allows for more precise rotational movements, which is why the metric ISO fine thread has also become established for set screws in measuring instruments.

The dimensions for the metric fine thread are specified in the standards DIN 13-2 to DIN 13-11. Thus, for the metric fine thread, there are multiple standards, unlike the standard thread, which has only one.

The dimensions for the metric fine thread are given in mm. The flank angle is 60°. The pitch, which is the distance between two thread peaks, is also given in mm.

For the thread designation of the metric fine thread, two approaches have been established. The usual variant sees the abbreviation M followed by the external diameter and pitch, as in M 24 x 1.5. To better distinguish it from the standard thread, a variant using the abbreviation MF followed by the external diameter is also used. The example above can thus also be denoted as MF 24 x 1.5.

Unlike the standard thread, there is not just one thread table for the metric fine thread but ten different ones. Each contains a range of sizes, some of which overlap. Generally, the external diameters increase with ascending standard numbers. DIN 13-11, for example, covers thread sizes from 130 to 1000 mm in diameter. The multitude of standards means that for the metric fine thread, different combinations of the same external diameter with different pitches are possible – sometimes even within the same standard.

Below, you will find all ten DIN tables for the metric ISO fine thread. Please click on the desired DIN standard to access the corresponding table. There you will also find, alongside the external diameter and pitch, information on the appropriate core hole diameter you need for threading.