Square bars are a suitable starting format when flat-sided machine parts with about the same width and thickness are to be manufactured. Their dimensional tolerances are better than for flat bars and corners are relatively sharp. A small, but limited, shape deviation from a perfectly square cross section is considered acceptable.

Most square-bar articles in stock are hot-rolled but some larger sizes are forged. In both cases, the surface is oxidised and some small, shallow surface defects are to be expected.