Sudoku365
Hard Sudoku for Thursday, December 31, 2026
Hard Sudoku · Thursday, December 31, 2026 · Solution: sudoku365.com/daily/2026/12/31/hard
About This Hard Sudoku Puzzle
This hard Sudoku for Thursday, December 31, 2026 (12/31/2026) starts with 30 given numbers and has exactly one solution. Solved logically, this grid takes 50 naked singles, 1 hidden single, 2 locked-candidates steps, 8 naked pairs, 2 hidden pairs and 3 naked triples.
Hardest technique needed: Naked Triples. A solver that uses only human techniques finishes this puzzle without guessing. New to it? Read the Naked Triples guide.
Stuck? See the first moves
- Row 2, column 8 must be 5: every other digit is already in its row, column or box (naked single).
- Row 2, column 7 must be 6: every other digit is already in its row, column or box (naked single).
- Row 3, column 7 must be 4: every other digit is already in its row, column or box (naked single).
Show the answer to the December 31, 2026 hard Sudoku
| 1 | 6 | 5 | 8 | 3 | 4 | 2 | 7 | 9 |
| 4 | 8 | 3 | 7 | 2 | 9 | 6 | 5 | 1 |
| 7 | 2 | 9 | 5 | 1 | 6 | 4 | 3 | 8 |
| 9 | 5 | 4 | 1 | 6 | 7 | 8 | 2 | 3 |
| 3 | 1 | 8 | 4 | 5 | 2 | 9 | 6 | 7 |
| 6 | 7 | 2 | 9 | 8 | 3 | 5 | 1 | 4 |
| 2 | 9 | 1 | 3 | 4 | 5 | 7 | 8 | 6 |
| 8 | 4 | 6 | 2 | 7 | 1 | 3 | 9 | 5 |
| 5 | 3 | 7 | 6 | 9 | 8 | 1 | 4 | 2 |
Bold digits are the original clues.
Print This Puzzle
Press Print above for a clean, full-page copy of this grid — no download or sign-up needed. To get all four of this date's levels on one sheet, print the December 31 set with answers, or grab a printable Hard pack with four puzzles and their solutions. Want the answer on paper too? Print this puzzle in large print with its answer key, or print 7 days of Hard puzzles starting on this date.
How to Solve This Puzzle
Click any empty cell and enter a number from 1-9. Use logic to determine which numbers can fit in each cell based on the Sudoku rules: no repeating numbers in any row, column, or 3x3 box. Turn on Notes to pencil in candidates; they are cleared automatically when you place a digit in the same row, column or box. Stuck for good? Show Solution fills in the answer.
Keyboard Shortcuts
- 1-9: Enter number in selected cell
- Arrow Keys: Navigate between cells
- Backspace/Delete: Clear selected cell
- N: Toggle pencil-mark notes
- Ctrl+Z / ⌘Z: Undo
Tips for Hard Puzzles
- Apply Locked Candidates (Pointing Pairs) to eliminate options
- Look for Box-Line Reduction opportunities
- Maintain pencil marks (candidate notes) systematically
- Study our Locked Candidates tutorial