Play 16x16 Sudoku Online
The 16x16 sudoku is the long-distance event of number puzzles: 256 squares, the numbers 1 to 16 and blocks of 4x4. The rules are the same as in classic sudoku, but the scale turns it into a different experience. At Sudoku Sagax you play ad-free and with no sign-up required.
What is a 16x16 sudoku?
A 16x16 sudoku follows exactly the same rules as the classic 9x9, on a board four times the size. Instead of nine digits there are sixteen numbers, here simply 1 to 16, rather than the mix of digits and letters used elsewhere, because numbers stay unambiguous to read.
The blocks are square: four rows tall, four columns wide. Sixteen blocks make up the 256 squares.
The difference is not the difficulty of individual deductions but their sheer number. A 16x16 is less forgiving of inattention, because a mistake only surfaces much later; in return it offers a solving session you can genuinely sink into.
The rules, explained simply
The same three as always, just larger:
- Rows. Each of the sixteen rows contains every number from 1 to 16 exactly once.
- Columns. The same for each of the sixteen columns.
- Blocks. Each of the sixteen 4x4 blocks contains every number exactly once as well.
Every puzzle has exactly one solution; it simply takes longer to see everything.
Strategy for the big grid
What you can hold in your head on a 9x9 needs method here:
- Be systematic, not restless. Finish an area before moving on. Jumping around a 16x16 costs you the overview and makes you check the same places twice.
- Notes are mandatory. Nobody remembers sixteen candidates per square. Use the notes feature consistently; on a 16x16 it is a tool, not a comfort.
- Work number by number. Pick one number and look for its possible places across the whole board. That method scales with board size far better than working square by square.
- Exploit the block boundaries. Within a 4x4 block, one placed number constrains four rows and four columns at once. That interplay is stronger than on a 9x9 and the richest source of deductions.
16x16 at Sudoku Sagax
You will find 16x16 sudoku from the home screen under "All game types". It has its own levels, a separate leaderboard and its own trophy. Every level you solve counts towards your daily streak and the shared points pool.
Because a 16x16 takes considerably longer than a normal sudoku, a solved level carries correspondingly more weight in the shared scoring; it is the most heavily weighted puzzle type.
The keypad shows all sixteen keys and is fully usable on a phone; the numbers on the board scale with the board width so that two-digit values stay legible. Notes, error highlighting, hints and undo work as they do in classic sudoku.
Frequently asked questions
What is a 16x16 sudoku?
A 16x16 sudoku is a sudoku on a grid of 256 squares. Instead of nine digits it uses sixteen numbers, at Sudoku Sagax the numbers 1 to 16. The blocks are 4x4 squares, and the row, column and block rules are unchanged.
Why numbers instead of letters?
Many 16x16 sudokus use 0 to 9 plus A to F. We use the numbers 1 to 16 throughout, because they read without translation and cannot be confused with letters when you are making notes.
How long does a 16x16 sudoku take?
Considerably longer than a 9x9, anywhere from half an hour to well over one, depending on the level and your practice. That is exactly why it carries the most weight in the shared scoring.
Is a 16x16 sudoku harder?
The individual deductions are no harder, there are simply a great many more of them. The demanding part is the bookkeeping: with sixteen candidates per square you lose track quickly without consistent notes.
Related puzzles
- Extreme Sudoku If size is your thing, try hardness in 9x9: extreme demands real chains.
- Mini Sudoku The small counterpart: 6x6, solved in a couple of minutes.