Quantum calculator: a software maple package. The Quantum Calculator is a Maple program that can carry out computations in the small quantum cohomology ring of any Grassmannian of classical type. More precisely, it covers ordinary Grassmannians (type A) and Grassmannians of isotropic subspaces in a symplectic vector space (type C) or in an orthogonal vector space (type B or D). This software was written as part of a joint project with Andrew Kresch and Harry Tamvakis, aimed at studying the small quantum cohomology rings of submaximal isotropic and orthogonal Grassmannians. The Quantum Calculator is open source software (under the GNU General Public License).