Selector calculus is a form of calculus, employed by Burkhard Heim in formulating his Theory of Everything. It uses a differencing method similar to finite element methods to calculate derivatives and path integrals . Selector calculus was developed entirely by Heim, but due to difficulties in translating his work from German to English, his calculus may indeed be nearly equivalent to that of finite element methods for tensors.

The approach differs from the more prevalent form of differential calculus which does not place a finite lower bound on infintessimals. In selector calculus, the limit of Riemann sums taken to infinity has no physical interpretation, as the smallest unit of measure is a metron, rather than an infintessimal .

The discretization of selector calculus was used as an approach to model the observed quantised nature of fundamental particles. The use of this method by Heim results in a theory of particles which does not have infinities. This is in contrast to other particle models such as the Standard Model.