A buck–boost transformer is a type of transformer used to make adjustments to the voltage applied to alternating current equipment.

Buck–boost connections are used in several places such as uninterruptible power supply (UPS) units for computers, and in the tanning bed industry. Operating electrical equipment at other than its designed voltage may result in poor performance, short operating life, or possibly overheating and damage.

Buck–boost transformers can be used to power low voltage circuits including control, lighting circuits, or applications that require 12, 16, 24, 32 or 48 volts, consistent with the design's secondaries. The transformer is connected as an isolating transformer and the nameplate kVA rating is the transformer’s capacity[/align]