Time scale may refer to: Time standard, a specification of either the rate at which time passes, points in time, or both A duration or quantity of time: Orders of magnitude (time) as a power of 10 in seconds; A specific unit of time Geological time scale, a scale that divides up the history of Earth into scientifically meaningful periods In astronomy and physics: Dynamical time scale, in stellar physics, the time in which changes in one part of a body can be communicated to the rest of that body, or in celestial mechanics, a realization of a time-like argument based on a dynamical theory Nuclear timescale, an estimate of the lifetime of a star based solely on its rate of fuel consumption Thermal time scale, an estimate of the lifetime of a star once the fuel reserves at its center are used up In cosmology and particle physics: Planck time, the time scale beneath which quantum effects are comparable in significance to gravitational effects In mathematics: Time-scale calculus, the unification of the theory of difference equations with differential equations In music: Rhythm, a temporal pattern of events Time scale (music), which divides music into sections of time In project management: Man-hour, the time scale used in project management to account for human labor planned or utilized