Hard Sudoku Puzzles
Hard Sudoku Puzzles: free printable sudoku puzzles with an answer key. Fill every row, column and 3x3 box with the numbers 1 to 9. No guessing needed, but you will have to think! Great for ages 10 and up, early finishers and math centers.
- Size
- US Letter (8.5 × 11 in), fits A4
- 2 pages: the puzzle and its answer key
- Level
- Hard
- License
- Free for personal & classroom use
About this puzzle
Free printable sudoku puzzles with an answer key. Fill every row, column and 3x3 box with the numbers 1 to 9. No guessing needed, but you will have to think! Take your time: every hard puzzle is solvable by logic alone. Start with the row, column or box that has the most numbers filled in.
On this sheet
2 puzzles: puzzle 1 starts with 26 given numbers (3 6 2 9 1 2 7 5 7 5 3 4 ...); puzzle 2 starts with 24 given numbers (2 3 6 9 8 6 4 1 3 9 1 6 ...).
Tips for using it
- Write small pencil notes in the corners when two numbers could fit.
- Start with the easiest clue or the fullest row, column or box.
- Never guess: if you are stuck, look for one more thing you know for sure.
- Use a pencil and keep an eraser handy.
Printing tips
Download the PDF and print at 100% (or “fit to page” on A4). Page 1 is the puzzle and page 2 is the answer key with the answers in red; print just page 1 if you want to keep the answers for checking. The PNG shows page 1 only. Free for personal, family and classroom use.
