In linear algebra, Determinant of matrix is a value which is calculated from the elements of a square matrices. Determinant of matrix A is denoted by det(A), det A, or | A | and it is used for solving the system of linear equations. A matrix is said to be singular, if its determinant is 0. A matrix is said to be uni modular, if its determinant is 1. Use this online calculator to calculate the sum of 3x3 and 2x2 matrix determinants.