The 5 cm SK L/40 gun^{[Note 1]} was a German naval gun used in World War I and World War II.

The 5 cm SK L/40 gun was primarily used as an anti-torpedo boat gun aboard avisos, corvettes, gunboats, protected cruisers, submarines, torpedo boats, and unprotected cruisers. It was used by the navies of the German Empire, Nazi Germany, Belgium, and The Netherlands.

Ship classes that carried the 5 cm SK L/40 include:

• A-class torpedo boats
• Type UB II submarines
• S7-class torpedo boats
• S66-class torpedo boats
• G88-class torpedo boats
• S90-class torpedo boats
• Irene-class cruisers

• List of naval guns
• 5.2 cm SK L/55 naval gun

• Campbell, John (2002). Naval Weapons of World War Two. London: Conway Maritime Press. ISBN 0-87021-459-4.
• Reichs-Marine-Amt, ed. (1898). Die 5 cm Schnelllade-Kanone L/40 in Torpedoboots-Laffete C/92 und ihre Munition, nebst Vorschriften für die Behandlung und Bedienung. E. S. Mittler. OCLC 461072478.
• Friedman, Norman (2011). Naval Weapons of World War One: Guns, Torpedoes, Mines, and ASW Weapons of All Nations: An Illustrated Directory. Annapolis, MD: Naval Institute Press. ISBN 978-1848321007.

• http://www.navweaps.com/Weapons/WNGER_5cm-40_skc93.htm