The system has seven branches in the west, which were originally numbered from north to south from the S 1 (to Freising) to the S 7 (Wolfratshausen).
These are coupled with the five eastern branches.
Operational requirements have changed several times, particularly due to line extensions, resulting in random numbering in the east.
Two lines end at Munich East station (Ostbahnhof), these are currently S 1 and S 6.
The first change was made in June 1991 when the branch to Ebersberg changed from S 4 to S 5 as a requirement to shorten the travel time to and from Herrsching.
The line to Wolfratshausen was first called the S 10, but when it was connected to run over the trunk line it was changed to the S 7.

The S-Bahn branch in the east via Ismaning to the airport was designated as the S 8.
Later this was combined with the original line S 3, which shared part the route of the S 8, and the new route is called the S 8.
This eliminated route S 3.
The old route S 5 was later largely replaced by the current S 3, so there is currently no line S 5.

In addition there are lines S 20 and S 27, which run from Munich Central Station (Hauptbahnhof) and Pasing to Deisenhofen.
These two lines do not run through the trunk line tunnel.
The numbers beginning with 2 comes from the time of the introduction of these lines, as the line to Holzkirchen via Deisenhofen still had the number S 2 (instead of the current S 3).
These lines cross the Isar via Großhesselohe Bridge.

In the Deutsche Bahn time table, the S-Bahn lines are numbered from 999.1 to 999.8 and 999.20; line A is numbered as 999.30.
The system has seven branches in the west, which were originally numbered from north to south from the S 1 (to Freising) to the S 7 (Wolfratshausen). These are coupled with the five eastern branches. Operational requirements have changed several times, particularly due to line extensions, resulting in random numbering in the east. Two lines end at Munich East station (Ostbahnhof), these are currently S 1 and S 6. The first change was made in June 1991 when the branch to Ebersberg changed from S 4 to S 5 as a requirement to shorten the travel time to and from Herrsching. The line to Wolfratshausen was first called the S 10, but when it was connected to run over the trunk line it was changed to the S 7.
The S-Bahn branch in the east via Ismaning to the airport was designated as the S 8. Later this was combined with the original line S 3, which shared part the route of the S 8, and the new route is called the S 8. This eliminated route S 3. The old route S 5 was later largely replaced by the current S 3, so there is currently no line S 5.
In addition there are lines S 20 and S 27, which run from Munich Central Station (Hauptbahnhof) and Pasing to Deisenhofen. These two lines do not run through the trunk line tunnel. The numbers beginning with 2 comes from the time of the introduction of these lines, as the line to Holzkirchen via Deisenhofen still had the number S 2 (instead of the current S 3). These lines cross the Isar via Großhesselohe Bridge.
In the Deutsche Bahn time table, the S-Bahn lines are numbered from 999.1 to 999.8 and 999.20; line A is numbered as 999.30.
Munich S-Bahn