About this matrix calculator
Fill in the entries of matrices A and B (2×2, 3×3 or 4×4) and compute A+B, A−B, A×B, det(A), the transpose Aᵀ and the inverse A⁻¹ with one click. The determinant is computed by LU decomposition with partial pivoting — the same code path for 4×4, 3×3 and 2×2 — which is faster and numerically steadier than cofactor expansion; the inverse uses Gauss-Jordan elimination, turning [A|I] into [I|A⁻¹].
When det(A) is 0 the matrix is not invertible and the tool says so explicitly instead of returning meaningless numbers; result matrices are shown as tables with 12 significant digits, and floating-point noise such as 0.9999999999999998 is cleaned up to 1. Entries you have already typed are kept when you switch sizes. Everything is computed locally — your data never leaves the browser.