Kalachakra (Sanskrit: Kalacakra) is a Sanskrit term used in Tantric Buddhism that literally means 'time-wheel' or 'time-cycles'.

The Kalachakra tradition revolves around the concept of time (kala) and cycles (chakra): from the cycles of the planets; to the cycles of human breathing; it teaches the practice of working with the most subtle energies within one's body on the path to enlightenment.

The Kalachakra deity represents a Buddha and thus omniscience. Since Kalachakra is time and everything is under the influence of time; Kalachakra knows all. Whereas Kalachakri or Kalichakra; his spiritual consort and complement; is aware of everything that is timeless; untimebound or out of the realm of time. In Yab-yum; they are temporality and atemporality conjoined. Similarly; the wheel is without beginning or end.