If you are going to survive in the Viking age, you need a shield.  Fighting men used large, round, wooden shields gripped in the center from behind an iron boss.  The Norwegian Gulaþing and Frostaþing laws specify the construction of a shield. The shield should be made of wood with three iron bands and a handle fastened to the back side by iron nails. A later revision of the law says that the shield should be made of a double layer of boards (tvibyrðr), and the front should be painted red and white.

Typical Viking shields are 80-90cm (32-36 inches) in diameter. Some are larger, such as the Gokstad shields, which were 94cm (37in) across, although some shields are as small as 70cm (28in) in diameter. Presumably when a man made a shield for himself, he sized it to fit his body size and fighting style. A shield needs to be big enough to provide the desired protection but no bigger. A shield too small exposes additional lines of attack that an opponent might exploit, while a shield too large slows the defensive responses and exhausts the fighter unnecessarily.