Sudoku solver

Select the puzzle geometry that you would like to solve from the drop-down list below. Click on "New" to change the puzzle geometry or to clear an existing grid.

Here is the result of running the solver on the grid that you entered.

 2 

 1 

 5 

 8 

 7 

 6 

 9   4 

 3 

 6 

 7 

 8 

 3 

 9 

 4 

 2 

 1 

 5 
 3 

 4 

 9 

 1 

 2 

 5 

 8 

 7 

 6 

 5 

 8   7   4 

 3 

 2 

 1 

 6 

 9 

 4   6   3 

 9 

 8 

 1 

 7 

 5 

 2 

 1 

 9 

 2 

 6 

 5 

 7 

 3 

 8 

 4 

 8 

 2 

 6 

 7 

 4 

 3 

 5 

 9 

 1 

 7 

 3 

 4 

 5 

 1 

 9 

 6 

 2   8 

 9 

 5 

 1 

 2   6   8 

 4 

 3 

 7 

Difficulty rating: Diabolical

Solver ran for 23.40 seconds

Found cell e2 with single value 6
Removing value 6 from column, row and block for cell e2
Completed 1 of 81 cells.
Found cell d2 with single value 8
Removing value 8 from column, row and block for cell d2
Completed 2 of 81 cells.
Found cell i5 with single value 6
Removing value 6 from column, row and block for cell i5
Completed 3 of 81 cells.
Found cell g4 with single value 7
Removing value 7 from column, row and block for cell g4
Completed 4 of 81 cells.
Found cell e3 with single value 3
Removing value 3 from column, row and block for cell e3
Completed 5 of 81 cells.
Found cell g1 with single value 8
Removing value 8 from column, row and block for cell g1
Completed 6 of 81 cells.
Found cell e1 with single value 4
Removing value 4 from column, row and block for cell e1
Completed 7 of 81 cells.
Found cell i4 with single value 2
Removing value 2 from column, row and block for cell i4
Completed 8 of 81 cells.
Found cell d3 with single value 7
Removing value 7 from column, row and block for cell d3
Completed 9 of 81 cells.
Found cell a8 with single value 4
Removing value 4 from column, row and block for cell a8
Completed 10 of 81 cells.
Found cell h8 with single value 2
Removing value 2 from column, row and block for cell h8
Completed 11 of 81 cells.
Found cell b9 with single value 5
Removing value 5 from column, row and block for cell b9
Completed 12 of 81 cells.
Found cell d4 with single value 4
Removing value 4 from column, row and block for cell d4
Completed 13 of 81 cells.
Found cell i2 with single value 5
Removing value 5 from column, row and block for cell i2
Completed 14 of 81 cells.
Found cell i6 with single value 8
Removing value 8 from column, row and block for cell i6
Completed 15 of 81 cells.
Found cell b5 with single value 9
Removing value 9 from column, row and block for cell b5
Completed 16 of 81 cells.
Found cell c1 with single value 3
Removing value 3 from column, row and block for cell c1
Completed 17 of 81 cells.
Found cell c8 with single value 7
Removing value 7 from column, row and block for cell c8
Completed 18 of 81 cells.
Found cell h1 with single value 7
Removing value 7 from column, row and block for cell h1
Completed 19 of 81 cells.
Found cell f8 with single value 8
Removing value 8 from column, row and block for cell f8
Completed 20 of 81 cells.
Found cell c6 with single value 5
Removing value 5 from column, row and block for cell c6
Completed 21 of 81 cells.
Found cell d7 with single value 1
Removing value 1 from column, row and block for cell d7
Completed 22 of 81 cells.
Found cell a5 with single value 7
Removing value 7 from column, row and block for cell a5
Completed 23 of 81 cells.
Found cell b2 with single value 7
Removing value 7 from column, row and block for cell b2
Completed 24 of 81 cells.
Found cell h9 with single value 8
Removing value 8 from column, row and block for cell h9
Completed 25 of 81 cells.
Found cell e5 with single value 8
Removing value 8 from column, row and block for cell e5
Completed 26 of 81 cells.
Found cell a7 with single value 9
Removing value 9 from column, row and block for cell a7
Completed 27 of 81 cells.
Found cell f6 with single value 7
Removing value 7 from column, row and block for cell f6
Completed 28 of 81 cells.

Searching for single candidates
Search for single candidates unsuccessful

Searching for candidate lines
Removed 2 instances of value 1 from cells d4, f4, d5, f5, d6, f6
Removed 4 instances of value 3 from cells g7, h7, g8, h8, g9, h9
Removed 3 instances of value 6 from cells a2, b2, c2, a3, b3, c3
End of pass: removed 9 values from cells

Searching for single candidates
Search for single candidates unsuccessful

Searching for candidate lines
Search for candidate lines unsuccessful

Searching for naked pairs / triples / etc
Search for naked pairs / triples / etc. unsuccessful

Searching for hidden pairs / triples / etc
Search for hidden pairs / triples / etc. unsuccessful

Looking for X-Wing, etc patterns
Search for X-Wing, etc patterns unsuccessful

Looking for chains of values using simple coloring
Search with simple coloring unsuccessful

Looking for chains of values using multi coloring (single value type)
Search with multi coloring unsuccessful

Looking for forcing chains
Search for forcing chains unsuccessful

Looking for values which produce an invalid grid (Nishio)
Cell a2 contains the pair of values 1, 2
Testing value 1 in a2
Testing value 2 in a2
Cell e8 contains the pair of values 5, 9
Testing value 5 in e8
Testing value 9 in e8
Cell i1 contains the pair of values 1, 9
Testing value 1 in i1
Testing value 9 in i1
Cell c4 contains the pair of values 1, 6, 8
Testing value 1 in c4
Testing value 6 in c4
Testing value 8 in c4
Cell d1 contains the pair of values 2, 5, 9
Testing value 2 in d1
End of pass: removed value 2 from cell d1 as it produces an invalid grid

Searching for single candidates
Search for single candidates unsuccessful

Searching for candidate lines
Removed 3 instances of value 2 from cells f4, f5, f6, f7, f8, f9
End of pass: removed 3 values from cells

Searching for single candidates
Search for single candidates unsuccessful

Searching for candidate lines
Search for candidate lines unsuccessful

Searching for naked pairs / triples / etc
Search for naked pairs / triples / etc. unsuccessful

Searching for hidden pairs / triples / etc
Search for hidden pairs / triples / etc. unsuccessful

Looking for X-Wing, etc patterns
Search for X-Wing, etc patterns unsuccessful

Looking for chains of values using simple coloring
Search with simple coloring unsuccessful

Looking for chains of values using multi coloring (single value type)
Search with multi coloring unsuccessful

Looking for forcing chains
Search for forcing chains unsuccessful

Looking for values which produce an invalid grid (Nishio)
Cell a2 contains the pair of values 1, 2
Testing value 1 in a2
Testing value 2 in a2
Cell d1 contains the pair of values 5, 9
Testing value 5 in d1
Testing value 9 in d1
Cell e8 contains the pair of values 5, 9
Testing value 5 in e8
Testing value 9 in e8
Cell i1 contains the pair of values 1, 9
Testing value 9 in i1
Cell f5 contains the pair of values 3, 5
Testing value 5 in f5
Cell c4 contains the pair of values 1, 6, 8
Testing value 1 in c4
Testing value 6 in c4
Testing value 8 in c4
End of pass: removed value 8 from cell c4 as it produces an invalid grid

Searching for single candidates
Search for single candidates unsuccessful

Searching for candidate lines
Search for candidate lines unsuccessful

Searching for naked pairs / triples / etc
Search for naked pairs / triples / etc. unsuccessful

Searching for hidden pairs / triples / etc
Search for hidden pairs / triples / etc. unsuccessful

Looking for X-Wing, etc patterns
Search for X-Wing, etc patterns unsuccessful

Looking for chains of values using simple coloring
Search with simple coloring unsuccessful

Looking for chains of values using multi coloring (single value type)
Search with multi coloring unsuccessful

Looking for forcing chains
Search for forcing chains unsuccessful

Looking for values which produce an invalid grid (Nishio)
Cell c4 contains the pair of values 1, 6
Testing value 1 in c4
Testing value 6 in c4
Cell a2 contains the pair of values 1, 2
Testing value 1 in a2
Testing value 2 in a2
Cell d1 contains the pair of values 5, 9
Testing value 5 in d1
Testing value 9 in d1
Cell e8 contains the pair of values 5, 9
Testing value 5 in e8
Testing value 9 in e8
Cell i1 contains the pair of values 1, 9
Testing value 9 in i1
Cell f5 contains the pair of values 3, 5
Testing value 5 in f5
Cell i7 contains the pair of values 3, 4, 7
Testing value 3 in i7
End of pass: removed value 3 from cell i7 as it produces an invalid grid

Searching for single candidates
Search for single candidates unsuccessful

Searching for candidate lines
Search for candidate lines unsuccessful

Searching for naked pairs / triples / etc
Search for naked pairs / triples / etc. unsuccessful

Searching for hidden pairs / triples / etc
Search for hidden pairs / triples / etc. unsuccessful

Looking for X-Wing, etc patterns
Search for X-Wing, etc patterns unsuccessful

Looking for chains of values using simple coloring
Search with simple coloring unsuccessful

Looking for chains of values using multi coloring (single value type)
Search with multi coloring unsuccessful

Looking for forcing chains
Search for forcing chains unsuccessful

Looking for values which produce an invalid grid (Nishio)
Cell c4 contains the pair of values 1, 6
Testing value 1 in c4
Testing value 6 in c4
Cell a2 contains the pair of values 1, 2
Testing value 1 in a2
Testing value 2 in a2
Cell d1 contains the pair of values 5, 9
Testing value 5 in d1
Testing value 9 in d1
End of pass: removed value 9 from cell d1 as it produces an invalid grid
Cell d1 reduced to one value (5)
Found cell d1 with single value 5
Removing value 5 from column, row and block for cell d1
Completed 29 of 81 cells.

Searching for single candidates
End of pass: only cell a3 in this group contains the value 5
Found cell a3 with single value 5
Removing value 5 from column, row and block for cell a3
Completed 30 of 81 cells.

Searching for single candidates
End of pass: only cell a4 in this group contains the value 8
Found cell a4 with single value 8
Removing value 8 from column, row and block for cell a4
Completed 31 of 81 cells.

Searching for single candidates
Search for single candidates unsuccessful

Searching for candidate lines
Removed 2 instances of value 9 from cells f4, f5, f6, f7, f8, f9
End of pass: removed 2 values from cells

Searching for single candidates
Search for single candidates unsuccessful

Searching for candidate lines
Search for candidate lines unsuccessful

Searching for naked pairs / triples / etc
Processing chain of cells a1, b1, a2 for values 6, 1, 2 to remove from cells c1, b2, c2, a3, b3, c3
End of pass: removed 6 values from cells

Searching for single candidates
Search for single candidates unsuccessful

Searching for candidate lines
Search for candidate lines unsuccessful

Searching for naked pairs / triples / etc
Search for naked pairs / triples / etc. unsuccessful

Searching for hidden pairs / triples / etc
Search for hidden pairs / triples / etc. unsuccessful

Looking for X-Wing, etc patterns
Search for X-Wing, etc patterns unsuccessful

Looking for chains of values using simple coloring
Search with simple coloring unsuccessful

Looking for chains of values using multi coloring (single value type)
Search with multi coloring unsuccessful

Looking for forcing chains
Search for forcing chains unsuccessful

Looking for values which produce an invalid grid (Nishio)
Cell c4 contains the pair of values 1, 6
Testing value 1 in c4
Testing value 6 in c4
End of pass: removed value 6 from cell c4 as it produces an invalid grid
Cell c4 reduced to one value (1)
Found cell c4 with single value 1
Removing value 1 from column, row and block for cell c4
Completed 32 of 81 cells.

Searching for single candidates
End of pass: only cell e6 in this group contains the value 1
Found cell e6 with single value 1
Removing value 1 from column, row and block for cell e6
Completed 33 of 81 cells.

Searching for single candidates
Search for single candidates unsuccessful

Searching for candidate lines
Removed 3 instances of value 6 from cells a7, b7, a8, b8, a9, b9
Removed 1 instances of value 2 from cells d7, f7, d8, f8, d9, f9
End of pass: removed 4 values from cells

Searching for single candidates
Search for single candidates unsuccessful

Searching for candidate lines
Search for candidate lines unsuccessful

Searching for naked pairs / triples / etc
Processing chain of cells e4, e8 for values 9, 5 to remove from cells e1, e2, e3, e5, e6, e7, e9
End of pass: removed 2 values from cells

Searching for single candidates
Search for single candidates unsuccessful

Searching for candidate lines
Search for candidate lines unsuccessful

Searching for naked pairs / triples / etc
Search for naked pairs / triples / etc. unsuccessful

Searching for hidden pairs / triples / etc
Search for hidden pairs / triples / etc. unsuccessful

Looking for X-Wing, etc patterns
Search for X-Wing, etc patterns unsuccessful

Looking for chains of values using simple coloring
Search with simple coloring unsuccessful

Looking for chains of values using multi coloring (single value type)
Search with multi coloring unsuccessful

Looking for forcing chains
Search for forcing chains unsuccessful

Looking for values which produce an invalid grid (Nishio)
Cell a2 contains the pair of values 1, 2
Testing value 1 in a2
Testing value 2 in a2
End of pass: removed value 2 from cell a2 as it produces an invalid grid
Cell a2 reduced to one value (1)
Found cell a2 with single value 1
Removing value 1 from column, row and block for cell a2
Completed 34 of 81 cells.

Searching for single candidates
End of pass: only cell b8 in this group contains the value 1
Found cell b8 with single value 1
Removing value 1 from column, row and block for cell b8
Completed 35 of 81 cells.

Searching for single candidates
Search for single candidates unsuccessful

Searching for candidate lines
Removed 1 instances of value 2 from cells d1, e1, f1, g1, h1, i1
End of pass: removed 1 values from cells

Searching for single candidates
Search for single candidates unsuccessful

Searching for candidate lines
Search for candidate lines unsuccessful

Searching for naked pairs / triples / etc
Search for naked pairs / triples / etc. unsuccessful

Searching for hidden pairs / triples / etc
Search for hidden pairs / triples / etc. unsuccessful

Looking for X-Wing, etc patterns
Search for X-Wing, etc patterns unsuccessful

Looking for chains of values using simple coloring
Search with simple coloring unsuccessful

Looking for chains of values using multi coloring (single value type)
Search with multi coloring unsuccessful

Looking for forcing chains
Search for forcing chains unsuccessful

Looking for values which produce an invalid grid (Nishio)
Cell i7 contains the pair of values 4, 7
Testing value 4 in i7
Testing value 7 in i7
Cell b3 contains the pair of values 4, 8
Testing value 4 in b3
End of pass: removed value 4 from cell b3 as it produces an invalid grid
Cell b3 reduced to one value (8)
Found cell b3 with single value 8
Removing value 8 from column, row and block for cell b3
Completed 36 of 81 cells.

Searching for single candidates
End of pass: only cell b6 in this group contains the value 4
Found cell b6 with single value 4
Removing value 4 from column, row and block for cell b6
Completed 37 of 81 cells.
Cell c5 reduced to one value (2)
Found cell c5 with single value 2
Removing value 2 from column, row and block for cell c5
Completed 38 of 81 cells.
Cell c9 reduced to one value (6)
Cell d5 reduced to one value (3)
Found cell c9 with single value 6
Removing value 6 from column, row and block for cell c9
Completed 39 of 81 cells.
Cell c7 reduced to one value (8)
Found cell c7 with single value 8
Removing value 8 from column, row and block for cell c7
Completed 40 of 81 cells.
Found cell d5 with single value 3
Removing value 3 from column, row and block for cell d5
Completed 41 of 81 cells.
Cell d9 reduced to one value (9)
Cell f5 reduced to one value (5)
Found cell d9 with single value 9
Removing value 9 from column, row and block for cell d9
Completed 42 of 81 cells.
Cell d8 reduced to one value (6)
Cell e8 reduced to one value (5)
Found cell d8 with single value 6
Removing value 6 from column, row and block for cell d8
Completed 43 of 81 cells.
Cell d6 reduced to one value (2)
Found cell d6 with single value 2
Removing value 2 from column, row and block for cell d6
Completed 44 of 81 cells.
Found cell e8 with single value 5
Removing value 5 from column, row and block for cell e8
Completed 45 of 81 cells.
Cell e4 reduced to one value (9)
Cell g8 reduced to one value (9)
Found cell e4 with single value 9
Removing value 9 from column, row and block for cell e4
Completed 46 of 81 cells.
Found cell g8 with single value 9
Removing value 9 from column, row and block for cell g8
Completed 47 of 81 cells.
Cell g6 reduced to one value (3)
Cell i8 reduced to one value (3)
Found cell g6 with single value 3
Removing value 3 from column, row and block for cell g6
Completed 48 of 81 cells.
Cell h6 reduced to one value (9)
Cell h4 reduced to one value (5)
Cell a6 reduced to one value (6)
Found cell h6 with single value 9
Removing value 9 from column, row and block for cell h6
Completed 49 of 81 cells.
Found cell h4 with single value 5
Removing value 5 from column, row and block for cell h4
Completed 50 of 81 cells.
Cell f4 reduced to one value (6)
Found cell f4 with single value 6
Removing value 6 from column, row and block for cell f4
Completed 51 of 81 cells.
Cell b4 reduced to one value (3)
Found cell b4 with single value 3
Removing value 3 from column, row and block for cell b4
Completed 52 of 81 cells.
Cell b7 reduced to one value (2)
Found cell b7 with single value 2
Removing value 2 from column, row and block for cell b7
Completed 53 of 81 cells.
Cell a9 reduced to one value (3)
Cell e7 reduced to one value (7)
Cell b1 reduced to one value (6)
Found cell a9 with single value 3
Removing value 3 from column, row and block for cell a9
Completed 54 of 81 cells.
Cell f9 reduced to one value (4)
Found cell f9 with single value 4
Removing value 4 from column, row and block for cell f9
Completed 55 of 81 cells.
Cell g9 reduced to one value (1)
Cell f7 reduced to one value (3)
Found cell g9 with single value 1
Removing value 1 from column, row and block for cell g9
Completed 56 of 81 cells.
Cell g5 reduced to one value (4)
Cell i9 reduced to one value (7)
Found cell g5 with single value 4
Removing value 4 from column, row and block for cell g5
Completed 57 of 81 cells.
Cell h5 reduced to one value (1)
Cell g2 reduced to one value (2)
Found cell h5 with single value 1
Removing value 1 from column, row and block for cell h5
Completed 58 of 81 cells.
Found cell g2 with single value 2
Removing value 2 from column, row and block for cell g2
Completed 59 of 81 cells.
Cell g3 reduced to one value (6)
Cell f2 reduced to one value (9)
Found cell g3 with single value 6
Removing value 6 from column, row and block for cell g3
Completed 60 of 81 cells.
Cell g7 reduced to one value (5)
Cell h3 reduced to one value (4)
Found cell g7 with single value 5
Removing value 5 from column, row and block for cell g7
Completed 61 of 81 cells.
Found cell h3 with single value 4
Removing value 4 from column, row and block for cell h3
Completed 62 of 81 cells.
Cell c3 reduced to one value (9)
Cell h7 reduced to one value (6)
Cell h2 reduced to one value (3)
Found cell c3 with single value 9
Removing value 9 from column, row and block for cell c3
Completed 63 of 81 cells.
Cell c2 reduced to one value (4)
Cell i3 reduced to one value (1)
Found cell c2 with single value 4
Removing value 4 from column, row and block for cell c2
Completed 64 of 81 cells.
Found cell i3 with single value 1
Removing value 1 from column, row and block for cell i3
Completed 65 of 81 cells.
Cell f3 reduced to one value (2)
Cell i1 reduced to one value (9)
Found cell f3 with single value 2
Removing value 2 from column, row and block for cell f3
Completed 66 of 81 cells.
Found cell i1 with single value 9
Removing value 9 from column, row and block for cell i1
Completed 67 of 81 cells.
Cell f1 reduced to one value (1)
Found cell f1 with single value 1
Removing value 1 from column, row and block for cell f1
Completed 68 of 81 cells.
Found cell h7 with single value 6
Removing value 6 from column, row and block for cell h7
Completed 69 of 81 cells.
Found cell h2 with single value 3
Removing value 3 from column, row and block for cell h2
Completed 70 of 81 cells.
Found cell f2 with single value 9
Removing value 9 from column, row and block for cell f2
Completed 71 of 81 cells.
Found cell i9 with single value 7
Removing value 7 from column, row and block for cell i9
Completed 72 of 81 cells.
Cell e9 reduced to one value (2)
Cell i7 reduced to one value (4)
Found cell e9 with single value 2
Removing value 2 from column, row and block for cell e9
Completed 73 of 81 cells.
Found cell i7 with single value 4
Removing value 4 from column, row and block for cell i7
Completed 74 of 81 cells.
Found cell f7 with single value 3
Removing value 3 from column, row and block for cell f7
Completed 75 of 81 cells.
Found cell e7 with single value 7
Removing value 7 from column, row and block for cell e7
Completed 76 of 81 cells.
Found cell b1 with single value 6
Removing value 6 from column, row and block for cell b1
Completed 77 of 81 cells.
Cell a1 reduced to one value (2)
Found cell a1 with single value 2
Removing value 2 from column, row and block for cell a1
Completed 78 of 81 cells.
Found cell a6 with single value 6
Removing value 6 from column, row and block for cell a6
Completed 79 of 81 cells.
Found cell i8 with single value 3
Removing value 3 from column, row and block for cell i8
Completed 80 of 81 cells.
Found cell f5 with single value 5
Removing value 5 from column, row and block for cell f5
Completed 81 of 81 cells.

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