Sudoku Difficulty Levels Explained: Easy to Extreme
Sudoku sites and apps all offer levels named Easy, Medium, Hard and so on, but the names mean different things in different places. Here is exactly what each level means on this site: how many givens the board starts with, which solving techniques it requires, and who it suits. The numbers come from the generator itself, which measures every puzzle before it is shown to you, and they were calibrated against a sample of boards from the most popular Sudoku site so that our levels feel familiar.
Sudoku difficulty levels chart
| Level | Givens | Empty cells | Techniques required |
|---|---|---|---|
| Easy | 38 | 43 | Naked singles only |
| Medium | 36–38 | 43–45 | Naked and hidden singles |
| Hard | 30 | 51 | Mostly naked singles, some hidden singles |
| Expert | 30–32 | 49–51 | Hidden singles throughout, occasional locked candidates |
| Master | 23–28 | 53–58 | Naked pairs, pointing pairs, box/line reduction |
| Extreme | 22–23 | 58–59 | All of the above plus X-Wing, XY-Wing or Swordfish |
What actually makes a Sudoku hard
Two things, and they are not the same. The first is the number of givens. Fewer givens means each empty cell has more candidates and each deduction is harder to see, even if the deductions themselves are simple. The second is the hardest technique required. A board that can be finished with singles is fundamentally easier than one that needs an X-Wing, regardless of how many cells are empty.
The two do not move in lockstep. Our Hard level has fewer givens than Expert, yet Expert is harder because it always demands hidden singles while most Hard boards yield to naked singles alone. Sites that grade only by counting givens produce levels that feel inconsistent; measuring the techniques is what keeps a label meaningful from one puzzle to the next.
How the levels are generated and graded
Each puzzle starts from a complete, randomly generated solution grid. Givens are removed one at a time, in random order, as long as the board keeps exactly one solution. The result is then handed to a solver that only knows human techniques: singles, then pairs and locked candidates, then nothing more. The hardest technique it needed becomes the puzzle's grade, and a puzzle is only accepted for a level if both its clue count and its grade match that level. A Medium board never secretly requires an X-Wing, and an Extreme board never collapses to plain scanning.
What is Evil Sudoku, and how is it different from Hard or Expert?
Evil is a name some sites give their hardest or second-hardest level, so what it means depends on where you play. Web Sudoku, one of the oldest Sudoku sites, has four levels, Easy, Medium, Hard and Evil, so there Evil is the top one. On sudoku.com the menu calls the level Master and its page also calls it Evil Sudoku; it sits between Expert and Extreme. Our Master level matches that band.
The difference from Hard and Expert is not only that fewer numbers are given. Hard and Expert boards here can be finished with singles, with an occasional locked candidate on Expert. Evil, our Master, starts with 23 to 28 givens and requires pairs and locked candidates: naked pairs, pointing pairs and box/line reduction. If you are looking for Evil Sudoku, play Master; for something harder still, try Extreme.
Which Sudoku level should I play?
- Never played, or rusty: Easy. Learn to see singles without notes.
- Comfortable with the rules: Medium. Cross-hatching becomes essential.
- Want a longer solve without new techniques: Hard. Same logic, far fewer givens.
- Ready to rely on notes: Expert, then Master.
- Know X-Wing and want a fight: Extreme.
A good rule: move up when a level feels routine, not when it merely feels possible. If you find yourself guessing, drop back one level and read the techniques guide.
Frequently asked questions
How many givens does each Sudoku level have?
On this site: Easy 38, Medium 36 to 38, Hard 30, Expert 30 to 32, Master 23 to 28 and Extreme 22 to 23. The minimum for any 9×9 Sudoku with a unique solution is 17.
Why does Expert have more givens than Hard?
Because difficulty is set by the techniques a puzzle needs, not only by counting givens. Expert boards are selected so that hidden singles are unavoidable and locked candidates sometimes appear, while most Hard boards can be finished with naked singles.
What does Evil mean in Sudoku?
Evil is the name some sites use for the level between Expert and Extreme. It corresponds to our Master level: 23 to 28 givens and puzzles that require naked pairs and locked candidates.
Does a Sudoku always have only one solution?
A well-made one does. Every puzzle generated here is checked for a unique solution before it is shown, which is what guarantees that logic alone can finish it.