The Piano Concerto No. 18 in B♭ major, K 456 is a piano concerto by Wolfgang Amadeus Mozart. In Mozart's own catalogue of his works, this concerto is dated 30 September 1784.

The Köchel catalogue is a chronological catalogue of compositions by Wolfgang Amadeus Mozart, originally created by Ludwig Ritter von Köchel, in which the entries are abbreviated K. or KV. Its numbers reflect the ongoing task of compiling the chronology of Mozart's works, and provide a shorthand reference to the compositions.