[1] Operated by Metro Trains Melbourne, it is the city's fourth shortest metropolitan railway line at 17.9 kilometres (11.1 mi).

[2] The line operates from approximately 5am to 12am, daily, with 24 hour service available on Friday and Saturday nights.

[3] Trains on the Sandringham line run with a two three-car formations of Comeng or Siemens Nexas trainsets.

[5] The line was built to connect Melbourne with the suburbs of Balaclava, Elsternwick, Brighton, and Sandringham, amongst others.

[6] The Melbourne and Suburban Railway Company opened their line from Princes Bridge (later amalgamated with Flinders Street station) to a temporary station on Punt Road in February 1859, then to Cremorne (now closed) in December of that year.

In 1985, two Sandringham trains each way were altered to run via the underground loop, and in 1987, with the Port Melbourne and St Kilda lines converted to light rail operation, all off-peak and many peak trains were routed via the underground loop.

[citation needed] The commencement of operations involved the service stopping at three new stations—Parliament, Melbourne Central (formally Museum), and Flagstaff.

[8] The Loop follows La Trobe and Spring Streets along the northern and eastern edges of the Hoddle Grid.

[9] From 2021, Sandringham line services stopped operating through the loop as part of a timetable restructure.

[10] In 2021, the metropolitan timetable underwent a major rewrite, resulting in all Sandringham line trains terminating at Flinders Street without operating through the City Loop.

[12] Stage 4 of the Network Development Plan – Metropolitan Rail proposed that the Upfield and Sandringham lines be joined via a reconfigured City Loop sometime in the 2030s.

[25] The Sandringham line uses two different types of electric multiple unit (EMU) trains that are operated in a split six-car configuration.

The primary rolling stock featured on the line is the Comeng EMUs contain three doors per side on each carriage and can accommodate up to 556 seated passengers in each six-car configuration.

Since 2021, Comeng EMUs are progressively being retired as new rolling stock is introduced to the rail network.

[28] The second type of rolling stock is the Siemens Nexas EMUs contain two doors per side on each carriage and can accommodate up to 432 seated passengers in each six-car configuration.

From 1991, the line went back to using the regular Hitachi and Comeng trains until its displacement with the Siemens EMU.

In compliance with the Disability Discrimination Act of 1992, all stations that are new-built or rebuilt are fully accessible and comply with these guidelines.