23 mm caliber is a specific size of popular autocannon ammunition.

This ammunition size has been widely used in many conflicts worldwide. Examples of armaments using it are:

• 23×115mm caliber, used on many Soviet and Russian airplanes
• 23×122mm^[1]
• 23×139mmSR
• 23×152mmB caliber, used on Ilyushin Il-2 attack plane as well as on later Soviet anti-aircraft guns
• 23×260mm caliber, telescoped ammunition used on the Rikhter R-23 autocannon^[2]