Standard 9×9 · Free
Classic Sudoku — the original 9×9
No killer cages, no overlapping grids — just classic Sudoku online. Play a Medium board below, or jump into today's daily set.
Play now · medium
Tap a cell, then a number
The three classic Sudoku rules
- Rows: each of the nine rows contains 1–9 once.
- Columns: each of the nine columns contains 1–9 once.
- Boxes: each of the nine 3×3 boxes contains 1–9 once.
Every well-formed classic Sudoku has exactly one solution. Zeloku’s generator checks uniqueness before a board is shown, so you never waste time on a broken grid.
Classic Sudoku difficulty ladder
- Easy classic — ~38 clues, singles-heavy
- Medium classic — pairs and pointing patterns
- Hard classic — candidate tracking required
- Expert classic — low clues, advanced patterns
- Evil / Extreme — branding for the toughest classic boards
Learn classic techniques
Classic Sudoku improvement is almost entirely pattern recognition. Start with Hidden Single, then Naked Pair, then X-Wing. The full library lives under Learn.
FAQ
- What is classic Sudoku?
- Classic Sudoku is the original 9×9 number puzzle: fill the grid so every row, every column and every 3×3 box contains the digits 1–9 exactly once. No cages, no diagonals, no irregular regions — just the three core rules.
- How is classic Sudoku different from Killer or Samurai Sudoku?
- Killer Sudoku adds dashed cages with sum targets. Samurai Sudoku overlaps five classic grids. Jigsaw Sudoku uses irregular shapes instead of 3×3 boxes. Classic Sudoku uses only rows, columns and standard boxes.
- Is classic Sudoku good for beginners?
- Yes — start with Easy classic boards (more givens), then Medium. Learn Naked Single and Hidden Single before trying Hard or Expert classic puzzles.
- Can I print classic Sudoku?
- Yes. Zeloku’s printable packs are classic 9×9 grids in Easy, Medium and Hard. Open the Printable hub and download a free PDF.