What an inverting buck-boost converter does
An inverting buck-boost converter takes a positive input voltage and produces a negative output voltage, and can make that output either larger or smaller in magnitude than the input depending on the duty cycle.
The formula used
For an ideal converter in continuous conduction mode, |Vout| = Vin × D / (1−D), where D is the switch duty cycle. Solving for D gives D = |Vout| / (Vin + |Vout|). Because the topology inverts polarity, the actual output is negative relative to the input’s ground reference.
This calculator assumes ideal, lossless components; real converters need a slightly higher duty cycle to make up for switch, diode and inductor losses. This tool is for general electronics planning and education, not a substitute for full converter design and simulation.