Depending on its function, a binary decoder will convert binary information from n input signals to as many as 2ⁿ unique output signals. Some decoders have less than 2ⁿ output lines; in such cases, at least one output pattern may be repeated for different input values.

A binary decoder is usually implemented as either a stand-alone integrated circuit (IC) or as part of a more complex IC. In the latter case the decoder may be synthesized by means of a hardware description language