Adaptive voltage scalers (AVSs), systems, and related methods are disclosed. The AVSs are configured to adaptively adjust voltage levels powering a functional circuit(s) based on target operating frequencies and delay variation conditions to avoid or reduce voltage margin. In one embodiment, the AVS includes an AVS database. The AVS database can be configured to store voltage levels for various operating frequencies of a functional circuit(s) to avoid or reduce voltage margin. The AVS database allows rapid voltage level decisions. The voltage levels stored in the AVS database may be initial, minimum, learned, populated, explored, backed out, temperature-based, and/or age-based voltage levels according to disclosed embodiments to further avoid or reduce voltage margin. An AVS module may be a software-based module that consults the AVS database to make voltage level decisions. Providing the AVS module as a software-based module may allow flexibility in configuring the AVS module and/or the AVS database.