Cofactor Matrix Calculator

Cofactor Matrix Calculator

Find the matrix of cofactors and the determinant for a 2x2 or 3x3 matrix.

Last updated: 2026-06-21T07:59:21.706Z
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Matrix cell inputs must be valid numbers, including decimals and negatives.

Cofactor matrix
det(A) =
5
Cofactor matrix
[4-1]
[-32]

What is a cofactor matrix?

A cofactor matrix replaces each entry with its signed minor. It is commonly used to compute the adjugate and the inverse of a matrix.

How to use it

1

Choose the size

Switch between 2x2 and 3x3 matrices.

2

Enter values

Invalid entries are rejected instead of being converted to zero.

3

Read the output

The result panel shows the determinant and the cofactor matrix.

Worked example

Matrix [[2, 3], [1, 4]]

Cofactor matrix = [[4, -1], [-3, 2]]

det(A) = 5

Frequently asked questions

What is the difference between a minor and a cofactor?

A cofactor is a minor multiplied by a sign determined by its position.

Can I use decimals?

Yes. Decimal and negative values are accepted.

Why does the inverse use cofactors?

The adjugate matrix is the transpose of the cofactor matrix, and it appears in the inverse formula.

Does this work for non-square matrices?

No. Cofactors are only defined for square matrices.

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