Free Sudoku Online

How to play Sudoku

A Sudoku is a 9×9 grid split into nine 3×3 boxes. Some cells already hold a digit; these are the givens. Your job is to fill every empty cell so that each row, each column and each 3×3 box contains the digits 1 to 9 exactly once. No arithmetic is involved: the digits are just nine different symbols, and the whole game is about where each one can and cannot go.

• Select a cell by tapping it, clicking it or moving there with the arrow keys.
• Enter a digit with the number pad or your keyboard. Backspace or the eraser clears it.
• Switch on Notes (or press N) to pencil in the candidates you are still considering.
• Undo and Redo have no limit, so you can explore an idea and step back.
• A Hint fills one cell and names the technique that proves it, so a hint also teaches.

Every puzzle on this page has exactly one solution, and you never have to guess. Before a puzzle is published, a backtracking solver confirms that only one completed grid fits the givens, and a second, human-style solver confirms that the grid can be finished with logic alone.

The four difficulty levels

Many sites label difficulty by the number of givens. That is a weak signal: a grid with few clues can be easy and a crowded one can be brutal. We grade every puzzle by the hardest technique a careful solver needs, always trying the simplest technique first. The clue count is only a secondary filter.

Each level also has its own page with unlimited puzzles, so you can practice one difficulty for as long as you like. A medium puzzle never needs an X-Wing, and an expert puzzle always needs at least one of the expert techniques at some point.

The Daily Sudoku

At the top of this page is today's Daily Sudoku. A new one appears at midnight in your own time zone, and everyone who plays on the same date gets the same grid, which makes it easy to compare times with friends. The week follows a gentle curve: it starts easy on Monday and builds up to an expert puzzle on Sunday.

Your score is your solving time, plus the number of mistakes and hints. Mistakes never end the game; there is no three-strikes rule. If you finish without revealing the solution, the puzzle counts toward your streak of consecutive days. When you are done you can share a short result line that shows your time and counts but never the grid itself.

Getting started: five habits that work

1. Scan for the digit that appears most often. If seven 4s are already placed, the last two 4s usually have very few possible homes.
2. Work box by box. For one digit, look at which rows and columns already contain it; the cells left over in the box are the only candidates.
3. Look for rows, columns or boxes with only one or two empty cells and finish them first.
4. When a quick scan finds nothing, switch to notes. Writing candidates for a whole box often reveals a cell with a single option.
5. If you get stuck, ask for one hint and read the technique name. It tells you which pattern to look for next time.

Notes are not cheating. Strong solvers use them on every hard grid. If you prefer to skip the bookkeeping, the menu has a button that fills in every candidate at once; it does not affect your daily score. With automatic note clearing switched on, placing a digit removes that digit from the notes in the same row, column and box.

More ways to play

• Unlimited levels: Easy, Medium, Hard and Expert each have their own page with thousands of checked puzzles. The address of each puzzle ends in #p= and a number, so you can bookmark or send one.
• Printable Sudoku: print 1, 2, 4 or 6 puzzles per page, from 1 to 10 pages, with an answer key at the end.
• Techniques guide: illustrated explanations of every technique our levels use, from singles to Swordfish.

Frequently asked questions

Is this Sudoku really free?

Yes. Every puzzle, level and printable sheet is free and works in your browser. There is no account, no download and no limit on how many games you play.

What time does the Daily Sudoku reset?

At midnight according to the clock on your own device. If you start yesterday's puzzle before midnight, you can still finish it afterwards and it keeps its original number.

Does every puzzle have only one solution?

Yes. Each puzzle is checked by a solver that counts every possible completion and is only accepted when there is exactly one. A second solver then checks that it can be finished without guessing.

What happens when I make a mistake?

With mistake checking on, a wrong digit turns red and is underlined, and the mistake counter goes up by one. The game never ends because of mistakes. You can switch checking off in the menu if you prefer to find errors yourself.

How do hints work?

A hint fills the selected cell, or the next cell a solver would fill, and shows the name of the technique that settles it. Hints are unlimited, and the number you used appears in your result.

Is my progress saved?

Yes, in this browser. If you close the tab or your phone switches apps, the grid, notes and timer are restored when you come back. You do not need an account, and if you want, device linking keeps your records in step across devices.

Does it work offline?

After your first visit the site can work without a connection. Today's puzzle and the puzzles your browser has already loaded stay playable offline.

Can I play on my phone?

Yes. The board and number pad fit on a small screen without scrolling, and there is a zoom mode in the menu if the cells feel too small. You can also add the site to your home screen.