Free Sudoku Online: 5 Levels and Daily Sudoku

Play free Sudoku online with no download and no sign-up. Pick one of five levels, from Easy to Evil, and fill the grid with the numbers 1 to 9. It works great on a phone, too.

Every day there is a new Daily Sudoku for each level, the same for every player, so you can build a streak of consecutive days.

How to play Sudoku online

Sudoku is a 9×9 grid divided into nine 3×3 boxes. Your job is to fill every empty square so that each row, each column and each box contains all the numbers from 1 to 9, with no repeats.

Select a square by tapping it (or with the arrow keys), then enter a number from the keypad. On a computer you can type it, too.
The numbers already in the grid are the clues. You can’t change them.
Not sure? Use Notes: write the possible numbers small in a square and erase them as you rule them out.
One solution only: every puzzle can be solved by pure logic. You never have to guess.

Sudoku levels: Easy, Medium, Hard, Expert and Evil

The level doesn’t depend on how many numbers are already in the grid. It depends on which techniques you need to solve it: the more advanced the technique, the harder the puzzle.

Easy: naked and hidden singles are enough, meaning squares where only one number fits. Ideal for beginners.
Medium: you also need the pointing pair, box/line reduction and pairs of numbers (naked pair, hidden pair).
Hard: triples (naked triple, hidden triple) and the X-Wing, a rectangle pattern across two rows and two columns.
Expert: calls for the XY-Wing, a chain of reasoning across three linked squares.
Evil: for people who have seen it all, with the Swordfish and the XYZ-Wing. Even an Evil Sudoku is solved by deduction alone, with no trial and error.

If you get stuck, the Hint button tells you which technique to use. It’s a good way to learn the ones you’ll need at the next level.

Daily Sudoku and your day streak

Switch from Free play to Daily Sudoku and you get five fresh puzzles, one per level, the same for everyone. Compare times with friends and build your Day streak by finishing a daily puzzle every day.

The daily puzzle changes at midnight on your phone or computer, so it always follows your own time zone. In Free play, you can start as many games as you like: we have 400 puzzles for each level, all generated by OneDayQuiz and each with a single solution.

Your record on each level counts only if you didn’t use hints. Stats and records are saved in your browser, and with an account they follow you to any device.

Notes, hints and checking your mistakes

Notes: write the possible numbers small. All notes fills them in for you, and with Remove notes when a number is placed turned on, notes that are no longer valid disappear on their own.
Hint: highlights the next square you can solve and names the technique. A hint adds 30 seconds, and that game doesn’t count toward your record.
Check: marks wrong numbers in red. If you prefer instant feedback, turn on Show mistakes right away in the settings.
Undo, Redo, Erase and Pause: go back as many times as you want, clear a square, or stop the clock when you need a break.

In the settings you can also turn on Highlight matching numbers, Show the timer, High contrast and Sounds.

Tips to solve Sudoku faster

Start with the most common numbers. If a number already appears eight times, the ninth spot is almost a gift.
Look for the only place. In a row, column or box, can a number really go in just one square?
Don’t guess. If a number isn’t certain, move on and look for another square. The puzzle can always be solved by reasoning.

Sudoku on your phone

The game is designed for smartphones first: big squares and keypad, no page scrolling while you play, and a count on each key of how many times that number is still missing. Close the page mid-game and you pick up right where you left off. Full screen gives you more room.

Online Sudoku vs. paper Sudoku

The rules and techniques are the same, and what you learn here carries over to the newspaper puzzle. Online you get Notes, mistake checking and hints; on paper you get the calm of a real pencil.

Got a puzzle from a newspaper or a book and you’re stuck? Type it into our Sudoku solver to see the solution, or follow it step by step.

Frequently asked questions

Is online Sudoku free?

Yes. It’s free, with no download and no sign-up. If you create an account, your stats and day streak are saved to your profile.

What is the difference between the Sudoku levels?

It depends on the techniques you need, not on how many numbers are already written in. Easy needs only singles. Evil needs the Swordfish and the XYZ-Wing.

Does every puzzle have only one solution?

Yes. OneDayQuiz creates the puzzles with a program that checks each one for a unique solution and its level. They are not copied from newspapers or other sites.

How does the Daily Sudoku work?

Each day there are five puzzles, one per level, the same for every player. Finish one every day to grow your day streak. New puzzles arrive at midnight in your time zone.

Can I play Sudoku on my phone?

Yes. The game is built mainly for phones: tap a square, then tap a number. If you close the page, your game is saved and you can pick it up again later.

More games and puzzles

If you like logic puzzles, try our logic riddles or the riddles section. To practice math, play the multiplication games or study the multiplication tables. To test your knowledge, head to the online quiz games and take the Quiz of the Day.