A square nut features a four-sided design. When compared to hexagonal nuts, square nuts create more contact area with the fastened component, resulting in enhanced resistance against loosening (although this also means increased resistance during tightening).

They are specifically engineered to pair with square head bolts and flat washers. They perform effectively in confined spaces and show improved durability against rounding off during multiple tightening/loosening cycles.

The downside of these nuts is that square configuration creates pointed corners that may potentially damage surrounding wood or metal materials where the nut is installed.