How this matrix calculator works
Enter the four entries of a 2×2 matrix: a and b on the first row, c and d on the second. The calculator finds the determinant with Determinant = a×d − b×c. For a=1, b=2, c=3, d=4 that is 1×4 − 2×3 = −2.0000. The result is shown to four decimal places.
Layout matches the on-page formula |a b; c d|. a is top-left, b top-right, c bottom-left, and d bottom-right. The identity matrix 1, 0, 0, 1 gives 1.0000. A diagonal matrix 2, 0, 0, 2 gives 4.0000. All four fields must be filled with finite numbers; otherwise the result stays “--.”
A non-zero determinant means the matrix is invertible. A zero determinant means it is singular: the rows are multiples of each other. a=2, b=3, c=4, d=6 gives 0.0000 because the second row is twice the first. Negatives are normal: a=5, b=3, c=2, d=1 gives −1.0000.
This page only computes the 2×2 determinant. It does not multiply matrices, find an inverse, or handle larger sizes. Check by hand with a×d minus b×c: for a=3, b=1, c=2, d=4 you get 12 − 2 = 10.0000.