Sudoku Difficulty Levels Explained: From Easy to Expert

If you have ever picked up a Sudoku book, you have seen the labels: Easy, Medium, Hard, and Expert. But have you ever wondered what actually determines these rankings? A puzzle's difficulty isn't about how many numbers are missing—it's about the complexity of the logic required to fill them in.

The Logic of Grading

Sudoku generators use "solvers" to test a grid. An Easy puzzle can be solved using simple scanning and naked singles. As you move to Hard and Expert, the solver must use advanced techniques like X-Wings, XY-Wings, or even "chains" to find the next number. If a human needs to look three or her steps ahead to make a deduction, the puzzle is graded as Expert.

Understanding these levels helps you choose the right challenge for your current skill level. You can play free Sudoku online at SudokuVault and test yourself across all three difficulty modes today.