TetrisClassics·Free to play
Sudoku
Fill each row, column and 3 × 3 box with the digits 1–9.
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SudokuHow to play Sudoku
Choose a level and a cell
Pick Easy, Medium, Hard or Expert, then select an empty cell and enter a digit using the keypad or keyboard. The selected row, column and box are shaded, matching digits light up, and the keypad counts how many of each digit remain.
Check the three groups
Each digit appears once in its row, column and 3 × 3 box. The timer runs while you play and your best time for each level is kept in this browser.
Use notes, hints and undo
Switch on Notes to record possibilities; a placed digit clears itself from neighbouring notes. Check highlights conflicts without filling the solution, Hint fills the selected cell, and Undo takes back the last entry.
Sudoku controls
- Tap a cell
- Select
- 1–9 / keypad
- Enter a digit
- Erase
- Clear a digit
- Hint / H
- Fill the selected cell
- Undo / Ctrl+Z
- Take back the last entry
This Sudoku game is built for Free Games. Read about controls and local storage.
Choose a related challenge
If this run is not going your way, Lights Out is close by in the same collection and tests a separate skill. Alternating between two games in one collection keeps a session interesting without asking you to learn a whole new set of controls.
What Sudoku is like to play
Sudoku is a quiet game of elimination. You get a 9 by 9 grid split into nine boxes of nine cells, and a handful of starting digits called clues. Your job is to fill every empty cell so that the digits 1 to 9 each appear once in every row, once in every column and once in every 3 by 3 box. The digits are only labels, and you could play the same puzzle with nine colours.
This edition builds a fresh grid every time you press New puzzle. Easy leaves 43 clues, Medium leaves 35 and Hard leaves 29, and each board is tested while it is being carved out so that exactly one solution survives. That matters more than it sounds. Because the answer is unique, every cell can be reasoned out, and a guess is never required. If you are new to that kind of reasoning, the Sudoku beginner guide walks through the first two techniques.
Tap a cell and type a digit, or use the on-screen keypad. Notes mode lets you park several candidates in one cell while you think. Check marks any conflicts you have created without revealing the answer. Starting clues are locked, so you can never damage the puzzle. Players who like this sort of careful narrowing usually also like Minesweeper.
Sudoku at a glance
| Genre | Puzzle Games |
|---|---|
| Challenge | Logic only, never guesswork |
| Pace | As slow as you like, no timer pressure |
| Original era | 1979, as Number Place in New York |
| Players | Single player |
| Controls | Tap a cell, 1–9 / keypad, Erase, Hint / H, Undo / Ctrl+Z |
| Cost | Free, with no account and no download |
Where Sudoku came from
The modern puzzle was invented by Howard Garns, a retired architect from Indiana. Dell Magazines printed it in 1979 under the name Number Place, and Garns was never credited by name in his lifetime. Latin squares, the mathematical idea underneath it, are far older and were studied by Leonhard Euler in the eighteenth century, but Euler never added the 3 by 3 box rule that gives Sudoku its character.
The puzzle travelled to Japan in 1984, where the publisher Nikoli ran it as Suji wa dokushin ni kagiru, meaning roughly "the digits must be single". The name was shortened to Sudoku. Nikoli also added two house rules that stuck: no more than 32 clues, and symmetrical clue patterns.
The worldwide boom came in late 2004, when a New Zealander named Wayne Gould persuaded The Times of London to print puzzles from a program he had written. Within a year Sudoku was in newspapers everywhere, and it has stayed there since. You can find more puzzles of that thinking sort in the puzzle games guide.
Ways people play Sudoku
- Killer Sudoku
- Cages of cells carry a sum, and the digits in each cage must add up to it without repeating. Arithmetic joins the logic, and many Killer grids start with no given digits at all.
- Samurai Sudoku
- Five 9 by 9 grids overlap at their corner boxes, so a digit placed in one grid constrains another. It is one long puzzle rather than five short ones.
- Jigsaw Sudoku
- The nine boxes become irregular shapes instead of neat 3 by 3 squares. Rows and columns work as normal, but your eye has to learn a new set of regions.
- Hyper and diagonal grids
- Extra regions are added: four shaded 3 by 3 squares in Hyper Sudoku, or the two main diagonals in the X variant. Each extra region is another place to spot a missing digit.
Sudoku questions and answers
Does Sudoku need any maths?
No. You never add, subtract or count anything. The digits 1 to 9 are simply nine distinct symbols, and the whole puzzle is about where each symbol can and cannot go. Swap them for nine animals and the puzzle plays identically.
Do I ever have to guess?
Not on this site. Every puzzle is generated by removing clues one at a time and putting a clue back whenever the grid stops having exactly one solution. A single solution means every cell can be deduced. If you feel stuck, you have missed something rather than met a fork.
What is the difference between easy, medium and hard?
The number of starting clues. Easy grids keep 43 filled cells, Medium keeps 35 and Hard keeps 29. Fewer clues mean you have to chain more steps together before a cell is forced, so hard boards take longer rather than demanding secret techniques.
What does Notes mode actually do?
It writes small candidate digits into a cell instead of an answer. Tap Notes, then tap digits to add or remove them from the selected cell. Entering a real answer clears that cell's notes. Notes are your own working and are never checked against the solution.
Does the Check button give away the answer?
No. Check only highlights digits that conflict with another digit you can already see, in the same row, column or box. A cell that is simply wrong in a way nothing contradicts yet will not be flagged.
Can I play Sudoku on a phone?
Yes. Tap a cell to select it, then tap a digit on the keypad below the grid. The Erase key clears your entry. No app, no account and no download is needed.
How do I get faster?
Scan by digit rather than by cell. Pick one number, look at where it already sits, and see which boxes have only one row or column left for it. Most beginners scan cell by cell, which is far slower.
If you like Sudoku, try these next
Four games from the same shelf, each with its own pace. The one-line summaries are how their own pages describe them.
| Game | What it is like | Pace | Play |
|---|---|---|---|
| Tetris | Seven falling shapes, one goal: clear the line. | Levels raise the drop speed | Play |
| Minesweeper | Reveal the safe squares and flag the hidden mines. | Bursts of thought, then quick clearing | Play |
| Lights Out | Switch off every light on the five-by-five board by toggling cells and their neighbors. | Two to ten minutes per board | Play |
Sudoku for beginners: start with what you know.
Rows, columns, boxes and the first two deductions worth learning.
