This online calculator may be used to calculate the determinant of a 3 by 3 matrix.

Let A be a 3 by 3 matrix given by
A = [[a , b , c] , [d , e , f] , [g , h , i]]
where [a , b , c] is the first row, [d , e , f] is the second row and [g , h , i] is the third row of the given matrix.
The determinant of matrix A is given by
det(A) = a (e i - h f) - d (b i - h c) + g (b f - e c)

Determinant calculator

More References and links

Calculate Determinant of a Matrix
Determinant of a 2 by 2 Matrix - Calculator
Math Calculators and Solvers.