Hard Sudoku Puzzles

A puzzle is rated Hard here when its hardest required technique is Hidden Triplet, Naked Quad or Hidden Quad — verified by a solver, not guessed from a star rating. 12,846 of the 65,284 puzzles in our library are rated Hard. How our difficulty ratings work.

Hard puzzles hinge on the larger subset patterns: Hidden Triplets and Naked or Hidden Quads. Spotting four candidates locked into four cells takes disciplined pencil marks and systematic scanning, and a single missed elimination can leave you stuck for a long time.

Play hard puzzles

  1. Hard puzzle #1 — 24 givens · needs Naked Single, Hidden Single, Naked Pair, Omission, Hidden Pair, Hidden Triplet
  2. Hard puzzle #2 — 24 givens · needs Naked Single, Hidden Single, Naked Pair, Omission, Hidden Pair, Naked Quad
  3. Hard puzzle #3 — 24 givens · needs Naked Single, Hidden Single, Omission, Hidden Quad
  4. Hard puzzle #4 — 24 givens · needs Naked Single, Hidden Single, Omission, Naked Triplet, Hidden Pair, Hidden Triplet
  5. Hard puzzle #5 — 25 givens · needs Naked Single, Hidden Single, Omission, Naked Triplet, Hidden Pair, Naked Quad
  6. Hard puzzle #6 — 25 givens · needs Naked Single, Hidden Single, Naked Pair, Omission, Naked Triplet, Hidden Pair, Hidden Quad
  7. Hard puzzle #7 — 24 givens · needs Naked Single, Hidden Single, Omission, Naked Triplet, Hidden Triplet
  8. Hard puzzle #8 — 24 givens · needs Naked Single, Hidden Single, Omission, Hidden Pair, Naked Quad
  9. Hard puzzle #9 — 24 givens · needs Naked Single, Hidden Single, Naked Pair, Omission, Hidden Quad
  10. Hard puzzle #10 — 24 givens · needs Naked Single, Hidden Single, Omission, Hidden Triplet
  11. Hard puzzle #11 — 24 givens · needs Naked Single, Hidden Single, Naked Pair, Omission, Naked Triplet, Hidden Triplet, Naked Quad
  12. Hard puzzle #12 — 25 givens · needs Naked Single, Hidden Single, Naked Pair, Omission, Hidden Quad
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Hard Sudoku FAQ

What makes a Sudoku puzzle hard?
On Precision Sudoku, difficulty is defined by the hardest technique a puzzle actually requires, verified by a solver — not by a vague star rating. A puzzle is rated Hard when the hardest move it needs is Hidden Triplet, Naked Quad, Hidden Quad.
How many hard Sudoku puzzles are there on Precision Sudoku?
12,846 of the 65,284 verified puzzles in the Precision Sudoku library are rated Hard, meaning their hardest required technique is Hidden Triplet, Naked Quad, Hidden Quad.
What techniques do I need to solve a hard Sudoku?
Hard puzzles hinge on the larger subset patterns: Hidden Triplets and Naked or Hidden Quads. Spotting four candidates locked into four cells takes disciplined pencil marks and systematic scanning, and a single missed elimination can leave you stuck for a long time.