Play Sudoku Online Free
Sudoku is a number-placement puzzle played on a 9×9 grid. Some cells start out filled; your job is to complete the rest so that every row, every column and every 3×3 box contains the digits 1 to 9 exactly once. No arithmetic is involved. Sudoku is a game of pure logic, which is why it works equally well for a five-minute break and a long evening.
This site gives you an unlimited supply of freshly generated puzzles in six difficulty levels, from Easy to Extreme. Every board has exactly one solution and can be solved by reasoning alone. Play in any modern browser on a desktop, tablet or phone. There is nothing to download and no account to create; your current game is saved in your browser so you can pick it up later.
What is Sudoku?
The puzzle we now call Sudoku first appeared in the late 1970s in American puzzle magazines under the name "Number Place". It became popular in Japan in the 1980s, where the publisher Nikoli gave it the name Sudoku, short for a phrase meaning "the digits must remain single". The worldwide boom came in 2004 and 2005, when British newspapers began printing a daily puzzle and the format spread to papers, books and apps all over the world.
Despite its reputation, Sudoku has nothing to do with mathematics. The digits are only labels; you could play with nine letters or nine colours. What the puzzle trains is careful observation, elimination and the habit of asking "what else could go here?" before committing to a move.
Sudoku rules (9×9)
- Each row must contain the digits 1 through 9 with no repeats.
- Each column must contain the digits 1 through 9 with no repeats.
- Each 3×3 box (the nine bold-outlined blocks) must contain the digits 1 through 9 with no repeats.
The numbers printed at the start, called givens or clues, are fixed. A well-made puzzle has exactly one solution, and every puzzle generated here is checked for that before it is shown to you. If you ever feel forced to guess, there is a deduction you have not spotted yet.
How to play Sudoku on this site: notes, hints and no timer if you want
- Select a cell by clicking or tapping it, then choose a digit from the number pad or press a key from 1 to 9. The selected cell's row, column and box are shaded, and every cell that already holds the same digit is highlighted.
- Notes switch the pad into pencil-mark mode so you can jot down candidate digits in the corners of a cell. When you place a digit, matching notes in the same row, column and box are cleared automatically.
- Mistakes are detected instantly: a wrong digit turns red and must be corrected or erased before you move on. Three mistakes end the game, with a second chance available.
- Hints fill in one correct cell. You get three per puzzle.
- Undo reverts your last move, Erase clears a cell, and the pause button hides the board while the clock stops.
- Prefer Sudoku without a timer? Turn the timer off in Settings. The mistake limit, auto-check and highlighting can be switched off there too.
- Keyboard shortcuts: arrow keys move the selection, Backspace erases, N toggles notes, H asks for a hint, Z undoes and Space pauses.
Sudoku difficulty levels
Difficulty is decided by two things: how many givens the board starts with, and which solving techniques the puzzle requires. The generator checks both, so an Easy puzzle never needs an advanced trick and an Extreme puzzle never turns out to be a pushover. The difficulty levels guide explains each level in detail, including why Expert has more givens than Hard.
| Level | Givens | What it takes |
|---|---|---|
| Easy | 38 | Scanning for cells with a single possible digit |
| Medium | 36–38 | Cross-hatching rows, columns and boxes for hidden singles |
| Hard | 30 | Long, systematic scanning with far fewer givens |
| Expert | 30–32 | Hidden singles throughout, occasional locked candidates |
| Master | 23–28 | Naked pairs, pointing pairs and disciplined notes |
| Extreme | 22–23 | Advanced patterns such as X-Wing and XY-Wing |
Sudoku solving techniques, from beginner to advanced
Every puzzle here can be finished by logic, and the techniques come in three tiers. Which ones a board needs is what sets its level:
- Singles: the last free cell in a row, column or box, the only cell left for a digit (a hidden single, found by cross-hatching) and the only digit left for a cell (a naked single). Singles alone finish Easy, Medium and Hard boards.
- Pairs and locked candidates: naked and hidden pairs, pointing pairs and box/line reduction. They start to appear on Expert, and Master boards need them.
- Patterns: X-Wing, XY-Wing, Swordfish and Skyscraper, which turn up on Extreme boards.
The Sudoku techniques guide explains each one with a diagram and the reasoning behind it.
Sudoku tips for beginners
- Start with the digit that appears most often on the board; it has the fewest places left to go.
- Work box by box before you work cell by cell. Boxes with six or seven givens usually give up a digit quickly.
- Do not guess. Every puzzle here can be finished with logic, and a guess that turns out wrong costs one of your three mistakes.
- Use notes as soon as a puzzle stops giving you obvious moves. Accurate notes turn Hard and Expert puzzles into a sequence of small, safe steps.
- When you are stuck, re-scan the grid for the digits you have not looked at in a while. New placements open up cells you dismissed earlier.
New to the game? Start with how to play Sudoku step by step. Stuck on a board? Work through the Sudoku tips for when you are stuck.
How the Sudoku score works
Every correct digit earns points that depend on the level and on your pace: the reward starts at the level's full value and drops a little every five seconds you spend between moves, down to a minimum. Completing a row, a column or a box with a single placement multiplies the reward by five for each unit you finish, so a cell that closes a row, its column and its box at once is worth fifteen times the base. Hints pay the base value, mistakes cost nothing but a life, and there is no bonus at the end, so a fast, tidy solve is the way to a high score. The full point table and what counts as a good score are on the scoring page.
Frequently asked questions
Is this Sudoku game free?
Yes. Every puzzle and every difficulty level is free to play, with no account and no download. The game runs entirely in your browser.
Do the puzzles always have one solution?
Yes. Each board is generated and then verified to have exactly one solution, so it can always be completed by logic alone without guessing.
Can I save my progress?
Your current game, including notes, time and score, is stored automatically in your browser. Come back to the same page on the same device and it resumes where you left off.
What happens after three mistakes?
The game ends and you are offered a second chance, which restores one life and lets you continue the same board. You can also turn the mistake limit off in Settings.
How many hints do I get?
Three per puzzle. Each hint fills in one correct cell and is worth the base score for that level rather than the full time-based reward.
Does Sudoku need math?
No. The digits are only symbols and nothing is added or multiplied. Sudoku is a logic puzzle that trains pattern recognition and careful elimination.
Is Sudoku good for your brain?
Sudoku exercises working memory, attention and logical reasoning, and many people find a daily puzzle a calming routine. Research on long-term cognitive benefits is mixed, so enjoy it as a mental workout rather than a medical treatment.
Can I play Sudoku without a timer?
Yes. Open Settings and switch the timer off. The clock still runs quietly for the score, but nothing is displayed and nothing pushes you to hurry.
Which level is right for a beginner?
Easy. Its 38 givens and singles-only logic let you learn scanning without notes. Move to Medium when finishing an Easy board feels routine; the difficulty levels guide describes what changes at each step.