A breaker bar is a long non-ratcheting bar that is used with socket wrench style sockets. Breaker bars are used to 'break loose' very tight fasteners because their additional length allows the same amount of force to generate significantly more torque than a standard length socket wrench. The use of a breaker bar also prevents damage to the ratcheting mechanism of a socket wrench. Often, after the first 1/2 turn of a fastener, the fastener is then loose enough to be turned with a socket wrench.

An improvised bar can be made with a length of metal pipe that has a wrench inserted into one end. This (pipe) device is often called a cheater bar.

Breaker bars are used to remove tire bolts as they are applied with great torque by an impact wrench. Breaker bars are used for roadside tire replacement to offer the driver the leverage needed to loosen the bolts.