Embodiments include systems and methods for measurement of signal propagation delay between Input/Output (IO) Loopback (IOLB) circuits. Embodiments include measurement of an output delay time of a first IOLB circuit and measurement of an input delay time of a second IOLB circuit. Embodiments also include measurement of a total delay time from an internal point of the first IOLB circuit to an internal point of the second IOLB circuit. Embodiments subtract from the measured total delay time, the measured output delay time of the first IOLB circuit and the measured input delay time of the second IOLB circuit to determine the time of flight of a signal between the I/O pads of the two IOLB circuits.