Methods and apparatuses related to guardband recovery using in situ characterization are disclosed. In one example, a system includes a target circuit, a voltage regulator to provide a variable voltage to, a phase-locked loop (PLL) to provide a variable clock to, and a temperature sensor to sense a temperature of the target circuit, and a control circuit, wherein the control circuit is to set up a characterization environment by setting a temperature, voltage, clock frequency, and workload of the target circuit, execute a plurality of tests on the target circuit, when the target circuit passes the plurality of tests, adjust the variable voltage to increase a likelihood of the target circuit failing the plurality of tests and repeat the plurality of tests, and when the target circuit fails the plurality of tests, adjust the variable voltage to decrease a likelihood of the target circuit failing the plurality of tests.