sudokly
23
9×9 · Easy to hard

Even-Odd Sudoku

Classic sudoku with a constraint on which cells hold even or odd digits.

Medium00:00✕ 0
About even-odd

What even-odd sudoku feels like.

Even-odd sudoku marks some cells in a way that fixes the parity of their digit. Cells with a shaded square must hold an even digit (2, 4, 6, 8); cells with a circle must hold an odd digit (1, 3, 5, 7, 9). Unmarked cells just follow the normal sudoku rules. Those parity hints narrow your candidates the moment you start.

Rules

  1. Standard 9×9 sudoku rules apply: digits 1–9 once per row, column, and 3×3 box.
  2. Cells marked with a shaded square must contain an even digit (2, 4, 6, or 8).
  3. Cells marked with a circle must contain an odd digit (1, 3, 5, 7, or 9).
  4. Unmarked cells carry no parity hint and may hold either an even or odd digit.
Key rule
Shaded cells must hold even digits
Difficulty range
Easy to hard
Tips
  • Even digits are rarer (only four of them per row), so shaded cells are heavily constrained. start there.
  • When scanning for a specific digit, immediately eliminate cells of the wrong parity.
  • Often more accessible than other variants because the parity constraint guides early moves.

Even-Odd Sudoku FAQ

Does the marking change the digit constraints?

No. The standard 1–9 row/column/box rules still apply. A square or circle only restricts which parity of digit can go in that cell; unmarked cells are unrestricted.

Are there always exactly four evens per row?

Yes. There are four even digits (2, 4, 6, 8), and each appears exactly once per row. The parity markers just reveal a few of those positions up front.

Is even-odd easier than classic?

At the same clue count, even-odd is easier because the parity hint reduces candidate sets immediately.

Are puzzles unique?

Yes. Uniqueness is verified.

Can the engine highlight parity errors?

Yes. when you enter a wrong-parity digit in a marked cell (an even digit in a circle, or an odd digit in a square), the cell flags the conflict.