Super Sudoku 16×16
The giant Sudoku challenge. Enter digits 1–9 and letters A–G (for 10–16) into the 256-cell grid.
or generate a puzzle to get started
About 16×16 Super Sudoku
The 16×16 Sudoku (also called Hexadoku) extends the classic grid to 256 cells arranged in sixteen 4×4 boxes. You use digits 1–9 plus letters A through G (representing 10–16).
The rules are identical to 9×9: every row, column, and 4×4 box must contain each of the 16 symbols exactly once. Our solver handles the extra complexity in seconds.
Frequently Asked Questions
What symbols does 16×16 Sudoku use?
Digits 1–9 and letters A (10), B (11), C (12), D (13), E (14), F (15), G (16).
How is 16×16 different from 9×9?
The grid is 16×16 (256 cells), boxes are 4×4, and 16 distinct symbols are used instead of 9.
Is the solver fast enough for 16×16?
Yes — the backtracking solver completes most 16×16 puzzles in under 5 seconds.
How to Play Super Sudoku 16×16
1 Rules
- ✓ Fill every row with all 16 symbols (digits 1–9 and letters A–G), no repeats.
- ✓ Fill every column with all 16 symbols, no repeats.
- ✓ Fill every 4×4 box with all 16 symbols, no repeats.
- ✓ Pre-filled clue cells cannot be changed.
2 Strategies
- 💡 Quadrant Scanning: The 16 quadrants (4×4 boxes) are your primary units. Start with the most-filled quadrant and use it to constrain its neighboring quadrants.
- 💡 Letter Zone Focus: Scan for letters A–G (10–16) as a dedicated pass — they are easier to overlook than digits. Treat each letter as a number to avoid confusion.
- 💡 Naked Pairs & Triples: With 16 candidates per unit, naked pairs appear constantly. Identifying them is the single most powerful technique for cutting through the complexity.
Tip: A 16×16 grid has 256 cells — manual solving is a serious commitment. Use Solve Animated to watch the backtracking algorithm work through it step by step and learn from the constraint logic.