Reintegral Calculus is the short form of Research in Integral Calculus. It is the collection of research papers and works on the topic entitled "A Study of Indefinite Nonintegrable Functions" submitted in the University Department of Mathematics, Vinoba Bhave University, Hazaribag, Jharkhand by the first author under the supervision of second author in 2012. It contains six conjectures on nonintegrable functions, dominating sequential functions corresponding to elementary trigonometric, hyperbolic, exponential, and logarithmic functions. The readers will find many scope of research in this field after going through the book.