Matrix Multiplication Calculator
Multiply two real matrices with independent row and column counts. This page opens on a 2×3 matrix times a 3×2 matrix, producing [58 64; 139 154] in exact arithmetic. Paste both complete grids or edit the cells; A’s column count must equal B’s row count. A column vector is an n×1 grid. The result has A’s rows and B’s columns, and a mismatch is explained with the two counts to change.
| 58 | 64 |
| 139 | 154 |
- Display
Row by column. The columns of A have to match the rows of B, and B × A is usually a different matrix.
Paste a whole matrix
Use one row per line or semicolon. Separate entries with spaces, tabs or commas; write fractions as 1/3. Brackets around each row are optional. Applying a matrix replaces that grid and its dimensions.
Each entry is a row of A paired off against a column of B and summed. Matrix multiplication is not commutative, so B × A is usually a different matrix.
Common questions
- How do I multiply a 2×3 matrix by a 3×2 matrix?
- Keep A at 2 rows and 3 columns and B at 3 rows and 2 columns. The shared inner size is 3, so the result is 2×2. With A = [1 2 3; 4 5 6] and B = [7 8; 9 10; 11 12], the first entry is 1×7 + 2×9 + 3×11 = 58, and the complete product is [58 64; 139 154]. The 2×3 times 3×2 example loads these exact values.
- Can I multiply a matrix by a vector?
- Yes. Enter a column vector in B with one column and as many rows as A has columns. [1 2 3; 4 5 6] times [1; 0; -1] gives [-2; -2]. A row vector belongs in a one-row grid, with the same inner-dimension rule. This is numeric matrix-vector multiplication; no symbolic or complex entries are accepted.
- How can I paste spreadsheet cells or another result?
- Open Paste a whole matrix. Use a new line or semicolon per row, with comma, tab or space separators between entries. Write fractions as 1/3. Text copies in bracketed rows can be pasted back directly. Apply to A and Apply to B validate the full grid before replacing its dimensions. A ragged or oversized grid is refused rather than truncated.
- Can I multiply three or more matrices?
- Multiply the first two, copy the exact Fraction result as text and apply it back to A. Apply the next matrix to B and multiply again, checking the new inner dimensions. This is a sequence of two-matrix products; there is no expression parser or simultaneous list of three matrices. Keep Fraction display when reusing a result, since Decimal copies reflect the chosen rounded display.
- Is A × B the same as B × A?
- Usually no. A = [1 2; 3 4] and B = [5 6; 7 8] give A × B = [19 22; 43 50], while B × A = [23 34; 31 46]. One order can even be undefined when dimensions differ. Change the grids deliberately to compute the other order; no hidden operand swap happens.
- Does it show steps or preserve my saved matrices?
- It shows the finished product, A’s determinant when square and the rank of A. The example above explains one row-column calculation, but the calculator does not print a full per-entry step trace. A visit or worked-example load alone does not replace a saved draft. Only fields you edit are saved. Text and LaTeX copies use the current display.
Exact: matrices are computed in rational arithmetic, so an inverse of an integer matrix is shown as fractions rather than rounded decimals, and a singular matrix is reported as singular instead of producing huge numbers.