Sudoku: play free online

Every puzzle has exactly one solution, so you reach the end by logic, never by guessing.

How to play sudoku: the rules

Sudoku has three rules and nothing else. Every row holds the digits 1 to 9 once. Every column holds them once. Every one of the nine 3×3 boxes holds them once. The given digits stay where they are and you fill in the empty cells. There is no maths involved: the digits could just as well be letters or colours, all that matters is that each one appears once in every row, column and box.

Sudoku difficulty levels

There are six levels: Easy (40 given cells), Medium (34), Hard (29), Expert (26), Master (24) and Extreme (22). The level is not a label. The generator checks which technique a grid really needs, from naked singles and hidden singles through pairs and pointing candidates to deeper methods on the master levels. Hard is really hard, and Easy works for your very first game.

Sudoku tips for beginners

Start with the digit that already appears most often and look at the boxes where it is still missing: often only one cell in such a box can take it. This is called scanning. A cell with only one possible digit left is a naked single, and a digit that fits in only one cell of a row, column or box is a hidden single. When the easy moves run out, write candidates as pencil notes and look for two cells in the same row, column or box that share the same two candidates: those two digits belong there, so you can remove them from the other cells of that unit. Never guess. If you are stuck, a hint shows the next logical step instead of the answer.

Daily sudoku challenge

One grid for every player in the world, the same for the whole day. Solve it and build a daily streak: the statistics track your win streak, best streak, win rate, average time and the record for every level.

Hints that teach instead of solving for you

Press Hint and the game shows the simplest logical step and highlights the cells that prove it, for example "in this row, 7 fits only here". You get three hints per game. Three mistakes end the game, but you can take a second chance after watching a short ad.

Controls on a phone and a computer

For comfortable play there are pencil notes with auto fill and clean up after each entry, undo, erase, instant mistake checking, highlighting of the same digits, large digits, a timer you can hide, a light, dark or system theme, sound and vibration. An interrupted game waits under Continue. On a computer you play with the keyboard: 1 to 9 enters a digit, N toggles notes, Backspace erases, Z undoes, H gives a hint and Esc pauses. On a phone you tap, and the board fits the screen in portrait and landscape.

Scores and the leaderboard

Your score depends on the level, time, mistakes and hints used, and the best games go to the klyo records board. See who leads today and try to overtake them.