Sudoku Difficulty Levels - What Makes a Puzzle Hard?

2026-05-13

What Determines Difficulty?

Sudoku difficulty isn't just about the number of empty cells. The complexity of techniques required to solve the puzzle is what truly defines difficulty.

Level Breakdown

Easy - Empty cells: 36-45 - Techniques: Naked Singles only - Time: 5-10 minutes

Medium - Empty cells: 30-35 - Techniques: Naked + Hidden Singles - Time: 10-20 minutes

Hard - Empty cells: 26-29 - Techniques: Naked Pairs, Pointing Pairs - Time: 20-40 minutes

Expert - Empty cells: 22-25 - Techniques: Hidden Pairs, Box/Line Reduction - Time: 30-60 minutes

Master / Extreme - Empty cells: 17-23 - Techniques: X-Wing, Swordfish, advanced chains - Time: 1+ hours