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 a database. The database can be configured to store voltage levels for various operating frequencies of a functional circuit(s) to avoid or reduce voltage margin. The database allows rapid voltage level decisions. In one embodiment, a voltage offset is added to a voltage level retrieved from the database corresponding to a target operating frequency of the functional circuit(s). In another embodiment, a voltage level is retrieved from the database corresponding to a target operating frequency for and a temperature level of the functional circuit(s). The AVS may partially or fully controllable by a software-based module that consults the database to make voltage level decisions.