A mathematical method is presented to obtain an isothermal transformation curve from a continuous cooling transformation (CCT) curve. It can also be used for transformations that occur during continuous heating rather than continuous cooling. The method is applied to nucleation and growth transformations and to grain growth. Furthermore, a new additivity rule based on non-isothermal transformation data, analogous to the traditional additivity rule based on isothermal transformation data, is introduced. Its use enables the calculation of the kinetics along an arbitrary cooling path relying solely on a CCT curve.