Multiply a Vector by a Matrix
Row vector-matrix multiplication. Runs entirely in your browser, so your data never leaves your device.
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Output
The result appears here as you type.
How to use Multiply a Vector by a Matrix
- 1. Paste the vector and matrix. Enter the row vector first, for example (1, 2), then a blank line, then the matrix rows. The vector's length must match the matrix's row count.
- 2. Read what the tool computes. The tool treats your vector as a row and multiplies it on the left of the matrix, producing a new row vector where each entry is a dot product with one matrix column.
- 3. Copy the resulting vector. The resulting row vector appears in the output pane. Copy it into your linear algebra notes, spreadsheet, or a script performing further transformations.
When to use Multiply a Vector by a Matrix
Multiply a Vector by a Matrix computes a row-vector-times-matrix product, the transpose-side counterpart to the usual matrix-times-column-vector operation. It is for whenever your linear algebra setup treats vectors as rows rather than columns.
- Working with row-vector conventions. Some fields, like certain robotics or graphics APIs, apply transformations by multiplying a row vector on the left of a matrix instead of a column vector on the right, and this matches that convention directly.
- Checking a homework problem stated with row vectors. A textbook problem defines the transformation as v times A rather than A times v, and you want to confirm your hand calculation follows the row-vector convention the problem specifies.
- Computing a weighted combination of matrix columns. The row vector acts as a set of weights, and multiplying it by the matrix gives a weighted sum of the matrix's columns, useful for understanding basis combinations in a linear algebra course.
- Verifying a state-vector update in reverse. A model updates a state vector by multiplying it on the left of a transition matrix, and you want to trace one manual update step to confirm your simulation code is orienting the multiplication correctly.
Examples
Enter the vector on one line, a blank line, then the matrix
Input
(1, 2) 1 2 3 4 5 6
Output
(9, 12, 15)
About the Multiply a Vector by a Matrix tool
Multiply a Vector by a Matrix is a free online tool that works entirely inside your web browser. Row vector-matrix multiplication. Because the processing happens on your own device, nothing you enter is uploaded, logged or stored anywhere.
This page is one of 234 Math utilities on EditSafely. Each one does a single job well, and all of them follow the same rule: your input stays on your machine.
There is nothing to configure. Provide the input and the result appears on its own. A worked example further down the page shows exactly what the tool produces for a real input.
Because nothing leaves your device, the tool is suitable for sensitive content such as internal documents, credentials or customer data. It also responds instantly, since every keystroke is handled on your own machine rather than by a remote API.
Frequently asked questions
Is Multiply a Vector by a Matrix free to use?
Yes, it is completely free. All 2,658 tools on EditSafely work without an account, a subscription or usage limits.
Is it safe to paste sensitive or confidential data?
Everything happens locally. Your browser downloads the tool's code once, then does all the processing itself; nothing you enter is transmitted, stored or logged. You can even go offline after the page loads and it will still work.
How much text can I process at once?
There is no fixed limit. Because the work happens on your own device rather than on a shared server, the practical ceiling is your machine's memory, which comfortably handles inputs far larger than typical online tools allow.
Do I need to sign up or install anything?
No. The tool works in any modern browser on desktop, tablet or phone. There is no account to create, no extension to add and no software to install.
How do I use the result?
The output panel has a one-click copy button, and you can keep refining the input while you work; the result updates in place as you type.