PaperKind puzzles · Hard · 9×9
Hard Sudoku · 1
NameTime
Fill every empty square so that each row, each column and each 3×3 box contains the numbers 1 to 9 exactly once.
63851384984915281342172944
Hard Sudoku · printable with solutions
Hard Sudoku puzzles for a real challenge.
Sparse 9×9 grids that reward patience and careful notes. Each still has exactly one solution.
At a glance
Who hard sudoku suits
Suitable for: Experienced solvers comfortable with pencil marks and looking for longer puzzles.
Starting clues: Hard 9×9 puzzles start with about 26 of 81 squares filled.
Every puzzle has exactly one solution, checked when it is created.
Printable puzzles
Hard Sudoku to print
Solutions stay hidden until you choose Show solution. Print the puzzle and solution separately.
PaperKind puzzles · Hard · 9×9Solution
Hard Sudoku · 1 — solution
Completed grid. Bold numbers were the starting clues.
462937815713825469985614237691548723827193546534276981246359178158762394379481652
PaperKind puzzles · Hard · 9×9
Hard Sudoku · 2
NameTime
Fill every empty square so that each row, each column and each 3×3 box contains the numbers 1 to 9 exactly once.
71855487896532479197832643
PaperKind puzzles · Hard · 9×9Solution
Hard Sudoku · 2 — solution
Completed grid. Bold numbers were the starting clues.
397651428841792365652483719163549872789216534524837196416978253938125647275364981
Hard Sudoku
Techniques worth knowing
Pointing pairs: if a number's only options inside a box lie in one row, that number cannot appear elsewhere in that row. Hidden singles: a number may have only one possible square in a row, even if that square has several candidates.
Keep your pencil marks tidy and complete. Hard puzzles often turn on noticing one small pattern, which is much easier when the notes are accurate.
Hard Sudoku
A note on difficulty
PaperKind grades puzzles by the number of starting clues. Clue count is a useful guide but not a perfect one, so two hard puzzles may feel quite different. If one is slow going, take a break and come back with fresh eyes.
Other levels
More Sudoku
Kids Sudoku4×4 puzzles start with about 8 of 16 squares filled; 6×6 puzzles start with about 20 of 36.Easy SudokuEasy 9×9 puzzles start with about 38 of 81 squares filled.Medium SudokuMedium 9×9 puzzles start with about 32 of 81 squares filled.Sudoku generatorMake a fresh puzzle at any level, with its solution.
Questions