U-1021 was fitted with five  torpedo tubes (four fitted at the bow and one at the stern), fourteen torpedoes, one  SK C/35 naval gun, (220 rounds), one  Flak M42 and two  C/30 anti-aircraft guns.
The U-1021 was outfitted with five torpedo launchers (four forward and one aft), fourteen torpedoes, a single naval gun of caliber SK C/35 firing 220 rounds, an anti-aircraft cannon Flak M42, and two additional anti-aircraft guns C/30.