Sudoku

Sudoku is the classic number-placement puzzle. A nine-by-nine grid is divided into nine boxes, and you must place the digits 1 to 9 so that each row, each column and each box contains every digit exactly once. Every puzzle here is generated and checked by a solver to have exactly one solution, so it can always be solved by logic. Choose from four levels, pencil in notes and use hints when you need them. Play Sudoku free online in your browser — no download or sign-up needed.

Time 0:00Mistakes 0Best —

Fill every row, column and 3×3 box with the digits 1 to 9. Select a square, then press a digit. Switch on Notes to pencil in candidates. Keyboard: arrows move, 1–9 enter a digit, Backspace erases, M toggles notes.

Game Information

Category
Puzzle Games
Players
Single player
Difficulty
Four levels from Easy to Expert
Game type
Numbers, Logic, Classic
Works on
Desktop and mobile browsers
Controls
  • Mouse or touch: select a square, then tap a digit on the pad
  • Keyboard: arrow keys move, 1 to 9 enter a digit, Backspace erases
  • Keyboard: M toggles notes, U undo, H hint, N new puzzle
Features
  • Four difficulty levels
  • Every puzzle has exactly one solution
  • Notes for candidates
  • Unlimited undo and a hint button
  • Highlights repeated digits and shows how many of each digit remain
  • Best time saved for each level

How to Play Sudoku

Objective

Fill every square so that each row, column and 3×3 box contains the digits 1 to 9 once.

Starting a game

Choose a level. Some squares already hold digits (shown in bold); the rest are empty.

Rules

  • Each row must contain the digits 1 to 9 once.
  • Each column must contain the digits 1 to 9 once.
  • Each of the nine 3×3 boxes must contain the digits 1 to 9 once.
  • Given digits cannot be changed.

Controls

  • Mouse or touch: select a square, then tap a digit on the pad
  • Keyboard: arrow keys move, 1 to 9 enter a digit, Backspace erases
  • Keyboard: M toggles notes, U undo, H hint, N new puzzle

Winning and losing

You win when the whole grid is filled correctly. Wrong digits are counted as mistakes but never end the game.

Tips and Strategies

  • Look for squares that have only one possible digit.
  • Scan a row, column or box for a digit that can go in only one place.
  • Use notes to keep track of candidates once the easy digits are done.
  • Repeated digits are highlighted, so check them as you go.
  • Use a hint only when you are truly stuck, then work out why that digit belongs there.

Frequently Asked Questions

Does every puzzle have a single solution?

Yes. Each puzzle is checked by a solver, so there is exactly one solution and no guessing is needed.

What are notes?

Notes let you write small candidate digits in a square. Placing a digit removes it from the notes of squares in the same row, column and box.

Is my time saved?

Your best time for each level is stored in your browser.

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