16x16 Sudoku

This free 16x16 sudoku tool lets you play and print 16x16 sudoku puzzles in your web browser. There is no sign-up and nothing to install, and the puzzles are made on your own device, so nothing is uploaded.

A 16x16 sudoku is a larger version of the classic puzzle. The grid has 16 rows, 16 columns and sixteen 4x4 boxes, and each row, column and box must contain the numbers 1 to 16 exactly once. With 256 cells, it is a much bigger puzzle than the usual 9x9 grid.

The tool opens on the Play tab, where you solve the puzzle on screen with pencil notes, hints and a timer. The Print tab makes sets of puzzles with answers for paper.

How to use the 16x16 Sudoku

The Play tab opens first. Follow these steps:

1. Tap or click an empty cell to select it.
2. Tap a number on the number pad, or type the digit on your keyboard. For 10 to 16, see the FAQ below.
3. Press the Pencil button, or the P or Space key, to write small candidate notes instead of a digit. Press it again to go back to placing digits.
4. Press Hint when you are stuck. It names the technique for the next step, such as Hidden Single or Naked Pair, highlights the cells and explains it in one sentence. If one of your digits is wrong, it asks you to fix that first.
5. Press Check to mark wrong cells in red and see how many cells are left.
6. Use Reveal cell or Show solution only when you want the answer. Start over clears your progress on the board, and New puzzle makes another one.

You can turn on “Mark repeated digits in red” to spot clashes, and “Remove pencil marks automatically” so that when you place a digit, its notes disappear from the cells it can see. Arrow keys move, digits enter, Backspace erases, and Ctrl/Cmd+Z and Ctrl/Cmd+Y undo and redo. Copy link gives a link that opens the same puzzle on another device. To print, use the Print tab.

What numbers are used in 16x16 sudoku?

A 16x16 sudoku uses the numbers 1 to 16. Each of the 16 rows, 16 columns and 16 boxes of size 4x4 must contain every number exactly once, so each number appears 16 times in the full grid, once in every row.

Some printed books label the 16 symbols as 0 to 9 and A to F instead. These are the same puzzle with different names. This site shows 1 to 16 throughout, on screen and on paper, and uses the letters A to G only as keyboard shortcuts and in shared links.

Because of these rules, a cell can only hold a number that is not already used in its row, column or box. Pencil notes list the numbers still possible for each cell. Two common logic moves help narrow those options. A Hidden Single is a number that has only one possible cell left in a row, column or box. A Naked Pair is two cells in the same unit that share the same two candidates, which lets you remove those two numbers from the other cells in that unit.

How many clues does a 16x16 sudoku have?

A 16x16 sudoku has fewer given numbers than its 256 cells, and the number of clues sets the difficulty. The generator on this site makes puzzles with about 141 clues for easy, about 123 for medium and about 108 for hard.

Fewer clues means less to start from, so hard puzzles need more logic and more pencil notes. A good place to begin on any level is the number that already appears most often: with many copies placed, its remaining positions are easy to pin down box by box. The clue count is the main difference between the levels. Every puzzle still has a single solution, so the clues you are given are enough to reach one answer.

Frequently asked questions

How do I play 16x16 sudoku?

Fill every empty cell so that each row, column and 4x4 box contains the numbers 1 to 16 once each. Start with cells that have only one possible number, and use pencil notes when several options remain.

Can I print 16x16 sudoku?

Yes. Open the Print tab, choose 1 or 2 puzzles per page, and pick Letter or A4 paper. Answers come at the end, 4 per page. A preview of the first page appears before you print, and in the browser print dialog you can choose Save as PDF to get a file.

How do I type 10 to 16?

Tap 10 to 16 on the number pad, or type on your keyboard using the letters A to G. A is 10, B is 11, C is 12, D is 13, E is 14, F is 15 and G is 16.

Can I continue a 16x16 sudoku later?

Yes. Your progress is saved in the browser on this device, so a reload continues the same puzzle. To open the same puzzle on another device, press Copy link and open the link there.

Does every 16x16 sudoku puzzle have one solution?

Yes. Each puzzle is checked by the site’s built-in solver to have exactly one solution before it is shown.

Can I play 16x16 sudoku on my phone?

Yes. On phones the board scales to fit the screen, and there is a zoom button if you need a closer view of the cells.

Related tools

• 4x4 sudoku: Use it for a quick, small puzzle before trying the full 16x16 grid.
• 6x6 sudoku: Choose it for a short step up in size from 4x4.
• Printable sudoku: Pick it when you want paper puzzles in standard sizes.
• Easy sudoku: Use it when you want a gentler puzzle with more clues.
• Sudoku generator: Use it to make new puzzles with the settings you choose.
• Sudoku solver: Use it when you want to check the answer to a puzzle you are working on.
• Blank sudoku grid: Use it when you want an empty grid to fill in by hand.