6×6 Sudoku — Free Mini Puzzles Online
A 6×6 Sudoku is thirty-six squares, the digits 1 to 6, and boxes two rows tall by three columns wide. It is the smallest grid that still plays like real Sudoku — small enough to finish in a few minutes, large enough that scanning alone will not always get you there.
The one thing that makes 6×6 different
On a 9×9 board the boxes are square, so a box spans the same three rows as it does columns and the geometry is symmetric. A 6×6 box is a rectangle — two rows by three columns — and that asymmetry is the whole character of the grid.
It means a row passes through only two boxes, while a column passes through three. So box/line reasoning is much stronger horizontally than vertically: if a digit in a box is confined to one row, it is eliminated from just one other box, but confine it to a column and you have eliminated it from two. Players arriving from the 9×9 board usually scan rows out of habit and miss this entirely.
Why the digits stop at 6
A Sudoku grid has to be a box tiled in both directions, so the side length is always the box's rows multiplied by its columns. A 2×3 box gives a 6×6 grid and six digits; a 2×2 box gives 4×4 and four. There is no 5×5 Sudoku, because 5 is prime and no rectangle tiles it.
Three levels, and what they ask for
- Gentle — Fourteen of the thirty-six squares filled. Every step can be found by scanning a row, a column or a 2×3 box.
- Regular — Twelve clues. Scanning alone stalls at least once, and you will need the digit that has only one home left in a unit.
- Tough — Ten clues, close to the fewest this grid supports. Expect to pencil in candidates and work a pair.
Ten clues is close to the floor for this grid. The generator removes a clue only while the puzzle still has exactly one answer, so on the hardest level it sometimes stops at eleven rather than ten — a puzzle with two valid answers is not a harder puzzle, it is a broken one.
This is not the children's board
The same 6×6 grid appears on Sudoku for kids, and it is a genuinely different puzzle there: sixteen of the thirty-six squares are filled in, there is no clock and no score, and nothing can be lost. Sixteen clues leaves a board that scanning finishes without a single real deduction, which is right for a six-year-old learning the rule and far too gentle for anyone else.
These levels dig to fourteen, twelve and ten. If you are here to teach a child, the kids page is the better one; if you are here for a quick puzzle, stay.
Where to go next
The techniques are the same ones the full board uses, just with fewer places to apply them — the hidden single and naked pairs guides both transfer directly. When the 6×6 stops being a challenge, the 9×9 easy puzzles are the natural step up, and printable sheets include 6×6 if you would rather work on paper. For a different kind of change, try Diagonal Sudoku or Killer Sudoku.
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