Hard Printable Sudoku
Hard printable sudoku puzzles have about 26 to 31 given numbers and need at least one advanced technique: a naked or hidden triple, or an X-Wing. Pairs and pointing pairs are not enough. Every puzzle is checked for exactly one solution, and the answers are printed on the last page.
Hard Sudoku generator
The generator needs JavaScript. The puzzle shown below is a fixed sample you can print with your browser.
#H-00001 · 30 given numbers
How to print it
- Choose a level and how many puzzles you want on each page.
- Choose the number of pages and A4 or US Letter paper.
- Press Print, or Download PDF to save the puzzles as a file.
- Keep the last page: it holds the answers, marked with each puzzle’s code.
The techniques behind a hard puzzle
- Naked triple: three cells in a unit whose candidates, together, are only three digits. Those three digits can be removed from the other cells of the unit. Not every cell needs all three digits.
- Hidden triple: three digits that, in one unit, can only go in the same three cells. The other candidates in those cells go.
- X-Wing: a digit that can only go in two cells in each of two rows, and those cells line up in the same two columns. The digit must take two opposite corners, so it can be removed from the rest of both columns. The same works with rows and columns swapped.
In our test of 1000 generated hard puzzles, each one needed a triple or an X-Wing at least once, and none needed anything beyond that.
Tips for hard sudoku
- Write every candidate in every empty cell before you look for patterns. Missing one candidate hides an X-Wing.
- For an X-Wing, pick one digit and look at the rows where it has exactly two places.
- Check your candidates after each placed number. A wrong candidate is the most common reason for getting stuck.
- When you are done, compare with the answer page using the puzzle code.
Ready for more? Try the expert sudoku.
All levels
| Level | Given numbers | Median | Techniques needed |
|---|---|---|---|
| Easy | 36–40 | 38 | Naked and hidden singles only |
| Medium | 30–35 | 31 | Singles plus naked or hidden pairs, pointing pairs and box/line reduction |
| Hard | 26–31 | 28 | All of the above plus naked or hidden triples or an X-Wing |
| Expert | 24–28 | 28 | Swordfish or XY-Wing, or longer chains that go beyond the techniques the grader knows |
Given numbers measured on 1000 generated puzzles per level (October 15, 2026). The level comes from which techniques a step-by-step solver needs, not from the count of given numbers.
Frequently asked questions
What makes a sudoku hard?
The reasoning it needs, more than the number of given digits. A hard puzzle on this site can only be finished with a triple or an X-Wing at some point. Puzzles with few given numbers can still be easy if singles are enough.
What is an X-Wing in sudoku?
An X-Wing is when one digit has exactly two possible cells in each of two rows, and those four cells form a rectangle across two columns. The digit must sit in two opposite corners, so it can be removed from the other cells in those two columns.
Is a hard sudoku solvable without guessing?
Yes. Every hard puzzle here has one solution and was solved by a program using only logical techniques, up to triples and X-Wings. If you feel you must guess, look again for a triple or an X-Wing.
How many given numbers does a hard sudoku have?
On this site, between 26 and 31 in a test of 1000 puzzles. The smallest number of givens any 9×9 sudoku with one solution can have is 17, which mathematicians proved in 2012, but the count alone does not set the level.
Are very hard and evil sudoku the same as hard?
Names differ between books and sites. Here, puzzles that need swordfish, XY-Wing or longer chains are called expert. If hard puzzles feel too easy, the expert page is the next step.
Last updated: October 15, 2026