How the Grade of a Sudoku Puzzle is Determined
1. Number of Given Clues
One of the first indicators is the number of pre-filled numbers (givens). Fewer givens usually means higher difficulty, but not always.
- Easy puzzles often have 30-35 givens.
- Moderate puzzles often have 25-30 givens.
- Hard puzzles may have 22-24 givens.
- Extreme puzzles can have as few as 17 givens.
2. Logical Depth and Steps Required
If a puzzle can be solved with basic scanning and single-candidate steps, it is easy. Advanced deductions push the grade higher.
3. Use of Advanced Techniques
Higher-grade puzzles may require X-Wing, Swordfish, and chaining techniques.
4. Branching and Trial-and-Error Factor
Well-designed Sudoku should be solvable without guessing. Puzzles that force deep branching are typically high-grade.
5. Computer Algorithm Testing
Many grading systems use solvers to detect the hardest required technique and assign the grade accordingly.
Next Steps
Continue Your Sudoku Path
These guides and puzzle pages are selected for the page you are on, so you can move naturally to the next skill, level, or practice route.
Techniques and Difficulty Guides
Move from the rating explanation into the real technique guides and difficulty pages those grades point toward.