Sudoku365
Hard Sudoku for Sunday, December 13, 2026
Hard Sudoku · Sunday, December 13, 2026 · Solution: sudoku365.com/daily/2026/12/13/hard
About This Hard Sudoku Puzzle
This hard Sudoku for Sunday, December 13, 2026 (12/13/2026) starts with 30 given numbers and has exactly one solution. Solved logically, this grid takes 42 naked singles, 9 hidden singles and 8 locked-candidates steps.
Hardest technique needed: Locked Candidates. A solver that uses only human techniques finishes this puzzle without guessing. New to it? Read the Locked Candidates guide.
Stuck? See the first moves
- Row 3, column 1 must be 2: every other digit is already in its row, column or box (naked single).
- 7 goes in row 1, column 5: it is the only cell in row 1 that can hold a 7 (hidden single).
- 5 goes in row 3, column 9: it is the only cell in row 3 that can hold a 5 (hidden single).
Show the answer to the December 13, 2026 hard Sudoku
| 8 | 9 | 5 | 1 | 7 | 6 | 2 | 4 | 3 |
| 3 | 1 | 4 | 5 | 2 | 9 | 6 | 8 | 7 |
| 2 | 6 | 7 | 8 | 3 | 4 | 1 | 9 | 5 |
| 4 | 2 | 8 | 7 | 5 | 1 | 3 | 6 | 9 |
| 1 | 7 | 6 | 3 | 9 | 8 | 4 | 5 | 2 |
| 9 | 5 | 3 | 6 | 4 | 2 | 7 | 1 | 8 |
| 5 | 4 | 2 | 9 | 6 | 7 | 8 | 3 | 1 |
| 6 | 3 | 1 | 2 | 8 | 5 | 9 | 7 | 4 |
| 7 | 8 | 9 | 4 | 1 | 3 | 5 | 2 | 6 |
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 13 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