All Sudoku Variants
16×16 · Size Variant

Sudoku 16×16

Also known as Hexadoku, Super Sudoku

A 16×16 grid with 4×4 boxes using digits 1–16 or hex characters 0–F — the most common large format.

1 2 3 4 5 6 7 8 9

An example 16×16 Sudoku (Hexadoku): sixteen symbols fill every row, column and 4×4 box (a few 1–9 shown).

16×16 Sudoku is the most common of the large formats: a sixteen-by-sixteen grid divided into 4×4 boxes, filled with sixteen different symbols. Those symbols are usually the numbers 1–16 or the hexadecimal characters 0–F. The rules are unchanged from Classic Sudoku — it is simply bigger, and it rewards patience far more than cleverness.

The rule: sixteen symbols per row, column and 4×4 box

Fill the grid so that every row, every column and every 4×4 box contains all sixteen symbols exactly once. A single 4×4 box already holds a full set — below, one box is filled with 1 through 16 to show the range you are working with.

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16

One 4×4 box holds all sixteen symbols (here 1–16). The full grid has sixteen such boxes.

Numbers or hexadecimal

Two labelling schemes are common. Puzzles for a general audience use the numbers 1–16, which are unambiguous but make each cell two digits wide. Puzzles aimed at programmers use the sixteen hexadecimal characters 0, 1, 2 … 9, A, B, C, D, E, F, which keep every cell to a single character and give the grid its "Hexadoku" nickname. The logic is identical either way — the symbols are just labels for sixteen distinct values.

Patience over difficulty

A 16×16 is not conceptually harder than a 9×9 — it uses the same techniques — but there is far more to track: sixteen candidates per cell, 256 cells, and boxes four wide. Careful pencil-marking becomes essential, because a single missed elimination is easy to make and slow to find. The reward is a long, absorbing solve; treat it as a marathon, keep your candidate marks tidy, and work one unit at a time.

Solving strategy

  • Pencil-mark methodically. With sixteen possible symbols per cell, candidate notes are not optional.
  • Work box by box. Finish scanning one 4×4 box before moving on, to avoid losing your place.
  • Hunt hidden singles per symbol. Take one symbol at a time and place it wherever it is confined to a single cell.
  • Use the same techniques as 9×9. Naked pairs, hidden singles and X-Wings all scale up unchanged.

Common mistakes

  • Sloppy candidate marks. On a grid this size, one wrong pencil mark can derail the whole solve.
  • Forgetting a symbol. All sixteen values must appear — it is easy to overlook one when scanning.
  • Mixing labelling schemes. Decide whether the grid uses 1–16 or 0–F and stick with it.
  • Rushing. The 16×16 rewards steady, careful work far more than speed.

Can I play it here?

Not yet — Sudoku 16×16 isn't one of the puzzle types SudokuStreak generates for now. But you can learn its rules above, and there's plenty here to sink your teeth into meanwhile: