Online Tool Store
Matrix Calculator
Multiply two matrices, or find the determinant and inverse of a matrix up to 4×4, with editable grids for each. Runs entirely in your browser.
🔒 This tool runs entirely in your browser. Your files are never uploaded to a server.
Matrix A
Matrix B
How it works
- Pick the size of Matrix A and Matrix B using the dropdowns above each grid, then fill in the values.
- Click Determinant of A or Inverse of A to calculate on Matrix A alone, or Multiply A × B to combine both.
- The result appears below — either a single number (determinant) or a full matrix.
The formulas
The determinant is calculated by cofactor expansion — for a 2×2 matrix it reduces to:
det([[a, b], [c, d]]) = ad − bc
The inverse is the adjugate matrix (the transpose of the cofactor matrix) divided by the determinant — which is exactly why a determinant of 0 means no inverse exists, since that would mean dividing by zero. Multiplication follows the standard row-by-column rule: each entry in the result is the dot product of a row from A and a column from B.
FAQ
Does anything I type get sent anywhere?
No. Every calculation happens locally in your browser — nothing you enter is uploaded.
Why can't I find the determinant or inverse of my matrix?
Both only exist for square matrices — the same number of rows and columns. A non-square matrix (like 2×3) can still be multiplied by a compatible matrix, but it has no determinant or inverse.
Why does it say Matrix A is "singular"?
A matrix is singular when its determinant is exactly 0 — that means it can't be inverted, the same way you can't divide a number by zero. Try changing a value slightly to see the inverse appear.
Why can't I multiply A by B?
Matrix multiplication requires A's number of columns to match B's number of rows — that's how the math is defined, not a limitation of this tool. Adjust either matrix's dimensions using the selectors above each grid.
What size matrices does this support?
Anywhere from 1×1 up to 4×4 for each matrix, which covers the vast majority of everyday linear algebra problems.
How we compare
| Feature | Online Tool Store | Graphing calculator | Doing it by hand |
|---|---|---|---|
| No file upload — runs in your browser | ✓ | N/A — physical device | ✓ |
| No device or app needed | ✓ | Requires owning one | ✓ |
| No arithmetic mistakes on larger matrices | ✓ | ✓ | Easy to slip up past 2×2 |
Doing it by hand is great for learning the method, and a graphing calculator works if you already own one. Matrix Calculator gets you the same answer instantly from any browser, with editable grids that make it easy to try different values without redoing the working.