What did Isaac Newton call his version of calculus?

Isaac Newton called his version of calculus the method of fluxions. In his terminology, changing quantities were “fluents,” while their instantaneous rates of change were “fluxions.” The notation he developed often represented a fluxion with a dot above a letter, such as ẋ for the rate of change of x with respect to time.

Newton developed the core of this mathematics during the mid-1660s, including the years when Cambridge was disrupted by the Great Plague. He used it to study curves, motion, changing quantities, and areas under curves. His treatise Method of Fluxions was completed in 1671, but it was not published until 1736, nine years after his death.

Newton’s terminology is often confused with the broader modern terms differential calculus or infinitesimal calculus. Those labels describe mathematical approaches or historical traditions, whereas “method of fluxions” is specifically Newton’s name for his system. Gottfried Wilhelm Leibniz developed an independent formulation, using notation such as dy/dx, which became more common. Newton’s dot notation remains familiar in physics, especially for time derivatives.