Sudoku generator, play it or print it.

A sudoku generator makes a new puzzle every time you press New puzzle, and checks that the puzzle has exactly one solution. You can play it right here with the keyboard or by tapping, use notes and hints, or print it as a PDF with the answers on the back. Pick Easy, Medium, Hard or Expert. If you already have a puzzle from a book or a paper, switch to Solve my puzzle and type it in to see the answer. Everything runs in your browser and nothing is uploaded.

How to play

1. Pick a Level. Easy is the starting choice. A new puzzle appears at once.
2. Click a square, or move with the arrow keys. Type 1 to 9, or tap a number below the grid, to put a digit in. 0, Backspace or Erase clears the square.
3. The aim is to fill every row, every column and every 3 by 3 box with the digits 1 to 9, each once.
4. Turn on Notes (or press N) to write small pencil marks. Placing a digit removes it from the notes of the squares that see it.
5. Use Check to mark wrong digits, Hint to fill one square, and Undo (or Z) to take a move back.
6. When the grid is full and right the page shows your time. A game with no hints can set a best time for that level, kept in this browser.

What the levels mean

These levels are defined by this page's own rules above, not by an official scale, so a hard puzzle here may not feel like a hard puzzle from a book. A one-solution puzzle needs at least 17 clues, so Expert still leaves a few more than that. Each time you ask for a Hard or Expert puzzle the page may try several grids, up to eight, until one fits its rule, and keeps the closest if none does.

Print sudoku as a PDF

1. Under Print sudoku, choose how many puzzles to put on a page: 1, 2 or 4.
2. Choose the number of pages, the level (or The level I am on), and the paper size.
3. Choose where the answers go. On the back of each page puts the answer page right after its puzzle page, so a double-sided print has them on the back. At the end puts them all after the last puzzle.
4. Press Download PDF. Each puzzle has a number you can use to find it again.

A request for 2 puzzles on a page and 3 pages makes 6 puzzles, and with answers on the back the file has 6 pages: 3 puzzle pages, each followed by its answer page. If you pick the level you are on, the first puzzle on the sheet is the one in the grid.

Share or repeat a puzzle

Every puzzle has a six-digit number, and the same number and level always make the same puzzle. Copy link to this puzzle puts the level and the number in the link, so a friend can open the identical grid. The number is also printed above each puzzle on a sheet.

Solve my puzzle

Switch to Solve my puzzle, click a square and type the digits from your book. The squares are black as you enter them. Press Solve. The page first checks that no row, column or box has a repeat, and that you gave at least 17 digits, the fewest a one-solution puzzle can have. Then it searches. It tells you if there is no solution, if there is more than one, or if there is exactly one. The squares it filled are green.

Tips for solving

• Scan for a digit that appears often. Look for a box where only one square can take it.
• Use notes only when the plain scan stops working, so the grid stays readable.
• If Check marks a digit, an earlier digit near it is usually wrong too.
• Do not guess. A puzzle with one solution can always be solved by thinking, even if Hard needs more steps.

For other printable puzzles, try the word search maker or the crossword maker. For a number game with sliding tiles, play 2048.