SM UB-28 was a German Type UB II submarine or U-boat in the German Imperial Navy () during World War I. The U-boat was ordered on 30 April 1915 and launched on 20 December 1915. She was commissioned into the German Imperial Navy on 27 December 1915 as SM UB-28."SM" stands for "Seiner Majestät" () and combined with the U for Unterseeboot would be translated as His Majesty's Submarine.
