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RREF Calculator

Separate entries with spaces or commas. Fractions such as 3/4 and decimals are accepted. Up to 10 × 10.

Rank —
Matrix size (rows × columns)
—
Pivot columns
—
Non-pivot columns
—
RREF (rows separated by |)
—

In reduced row echelon form (RREF) every pivot is 1, lies right of the pivot above, and is the only nonzero entry in its column. The augmented matrix [2 1 −1 8; −3 −1 2 −11; −2 1 2 −3] reduces to [1 0 0 2; 0 1 0 3; 0 0 1 −1], so x = 2, y = 3, z = −1.

About this tool

Students checking homework, engineers solving small linear systems and anyone verifying a hand reduction can paste a matrix here and see its reduced row echelon form. Type one row per line with entries separated by spaces or commas; fractions like 3/4 are read exactly as written. The result gives the rank, which columns hold pivots, how many columns are free, and the reduced rows shown as fractions where a small denominator fits. The working lists each row exchange, scaling and elimination in order. The arithmetic is floating point with partial pivoting, so entries that should be exactly zero are cleaned below 1e-10; for matrices with very large or very small entries in the same column, treat a borderline rank with care.

How to use it

  1. Type or paste the matrix

    Put each row on its own line and separate entries with spaces or commas. Decimals and fractions such as -5/3 both work.

  2. Read the rank and pivots

    The headline number is the rank. Pivot columns tell you which variables are basic; non-pivot columns are free variables.

  3. Check the reduced rows

    The table shows each row of the RREF. For an augmented system, the last column holds the solution when every variable column has a pivot.

  4. Follow the working

    The steps list every row operation, such as R2 = R2 − (−3/2) × R1, so you can compare against your own reduction.

Examples

Augmented 3 × 4 system

Matrix (one row per line)
2 1 -1 8 -3 -1 2 -11 -2 1 2 -3

Result Rank: 3
Matrix size (rows × columns): 3 × 4
Pivot columns: 1, 2, 3
Non-pivot columns: 1
RREF (rows separated by |): 1 0 0 2 | 0 1 0 3 | 0 0 1 -1

  1. Swap R1 and R2.
  2. R1 = R1 ÷ -3.
  3. R2 = R2 − (2) × R1.
  4. R3 = R3 − (-2) × R1.
  5. Swap R2 and R3.
  6. R2 = R2 ÷ 5/3.

The augmented matrix of three equations in x, y and z. Its last column after reduction reads off the solution x = 2, y = 3, z = −1.

The 1-to-9 matrix

Matrix (one row per line)
1 2 3 4 5 6 7 8 9

Result Rank: 2
Matrix size (rows × columns): 3 × 3
Pivot columns: 1, 2
Non-pivot columns: 1
RREF (rows separated by |): 1 0 -1 | 0 1 2 | 0 0 0

  1. Swap R1 and R3.
  2. R1 = R1 ÷ 7.
  3. R2 = R2 − (4) × R1.
  4. R3 = R3 − (1) × R1.
  5. Swap R2 and R3.
  6. R2 = R2 ÷ 6/7.

Row 3 equals twice row 2 minus row 1, so one row vanishes and the rank drops to 2.

How it is calculated

Gauss-Jordan: for each column, choose the largest pivot, scale its row to 1, then subtract multiples to clear the column above and below

Rᵢ
row i of the matrix
p
pivot entry used to scale the current row
rank
number of pivots, equal to the number of nonzero rows in the RREF

The tool walks the columns left to right. In each column it picks the row with the largest absolute value at or below the current row (partial pivoting, which limits rounding error), swaps it up, divides it by the pivot, and subtracts that row from every other row to zero the column. A column with no usable pivot is skipped and becomes a free column. The RREF of a matrix is unique, so any correct sequence of operations ends at the same matrix.

When not to use it

  • Matrices larger than 10 by 10 are rejected here; NumPy or MATLAB handle bigger ones.
  • For ill-conditioned matrices the floating-point rank can differ from the exact rank, so a proof needs exact rational software.

Common mistakes

  • Leaving out a zero coefficient shifts later entries into the wrong column, so write 0 for a missing variable.
  • Forgetting the constants column reduces the coefficient matrix instead of the system.
  • A zero row ending in a nonzero constant means the system is inconsistent, not solved.

Frequently asked questions

What is the difference between REF and RREF?

Row echelon form only requires each pivot to sit to the right of the one above, with zeros below it. Reduced row echelon form adds two conditions: every pivot equals 1 and every other entry in a pivot column is 0. A matrix has many row echelon forms but exactly one RREF.

How do I tell if a system has no solution?

Reduce the augmented matrix. If any row reads 0 0 … 0 | c with c not zero, the equations contradict each other and the system is inconsistent. Equivalently, the pivot list includes the last column.

What do the non-pivot columns mean?

In a coefficient or augmented matrix, each non-pivot variable column is a free variable that can take any value, so a consistent system with free columns has infinitely many solutions. The count also gives the dimension of the null space: columns minus rank.

Can I enter fractions?

Yes. Write entries like 2/3 or -7/4. Results are shown as fractions when the value matches a denominator up to 12, and as decimals to four places otherwise.

Why does the first step exchange rows when my textbook did not?

The tool uses partial pivoting: it moves the largest entry in the column into the pivot position to reduce rounding error. Textbooks often pick the first nonzero entry instead. The intermediate steps differ, but the final RREF is the same because it is unique.

How is rank related to invertibility?

A square n × n matrix is invertible exactly when its rank is n, which means its RREF is the identity matrix. A 3 × 3 matrix with rank 2, such as the 1-to-9 matrix, is singular and has determinant 0.

Cite this tool

Using this tool in an assignment, article or report? Copy a citation, or a link for your website.

APA

Tools Directory Editorial Team. (2026, October 24). RREF Calculator. Tools Directory. Retrieved October 26, 2026, from https://tools.milunir.com/math/algebra-tools/rref-calculator/

MLA

Tools Directory Editorial Team. “RREF Calculator.” Tools Directory, 24 Oct. 2026, https://tools.milunir.com/math/algebra-tools/rref-calculator/. Accessed 26 Oct. 2026.

Chicago

Tools Directory Editorial Team. “RREF Calculator.” Tools Directory. Last modified October 24, 2026. Accessed October 26, 2026. https://tools.milunir.com/math/algebra-tools/rref-calculator/.

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