Free Sudoku Online: A New Daily Sudoku Every Day

What sudoku is and why so many people play it every day

Sudoku is a logic puzzle that happens to use numbers. You never add, subtract or multiply anything; the digits 1 to 9 are just nine different symbols. You could swap them for colors, letters or pictures and the puzzle would work exactly the same way, which is why our sudoku for kids uses apples, leaves and stars. All you need is attention, patience and a willingness to ask "what can go here, and what can't?"

That simplicity is the reason sudoku has stayed popular for two decades. A daily sudoku takes anywhere from five minutes on an easy board to half an hour or more on a hard one, so it fits into a coffee break, a commute or the last quiet minutes before bed. Many players treat it as a small daily ritual: one board in the morning, the same time every day, and a quiet sense of progress as the boards that once felt hard start to fall faster.

Playing sudoku online has a few practical advantages over the newspaper version. You never run out of eraser, a wrong digit disappears with one tap, and the board itself points out a number that appears twice in a row, column or box. You also never run out of puzzles: when today's board is done, the New sudoku button deals a fresh one at the same level.

Sudoku rules: the whole game fits in one sentence

A sudoku board is a 9 × 9 grid. It is split into nine rows, nine columns and nine smaller 3 × 3 boxes. Some squares already hold a number; these are the givens, and they cannot be changed. Your job is to fill every empty square with a digit from 1 to 9 so that:

• each row contains every digit from 1 to 9 exactly once;
• each column contains every digit from 1 to 9 exactly once;
• each 3 × 3 box contains every digit from 1 to 9 exactly once.

That is all. There are no sums, no hidden rules and no time limit. Every digit you place immediately limits the other squares in the same row, the same column and the same box, and that chain of limits is what makes the puzzle solvable by pure logic. On this page any correct fill counts: as soon as the board is full and no digit repeats anywhere, you will see "Sudoku solved!"

How to play sudoku on this page, step by step

1. Pick a level. Use the chips above the board to choose easy, medium or hard. The main board on this page is today's medium sudoku.
2. Tap an empty square. The square is highlighted so you can see where the next digit will go.
3. Tap a number. The strip under the board holds the digits 1 to 9. Tap one and it is written into the selected square. This works the same on a phone, a tablet or a computer.
4. Fix mistakes. Changed your mind? Select the square again and tap a different number, or tap Erase to clear it.
5. Watch for red. If the same digit appears twice in a row, column or box, both squares turn red. That does not always mean your newest digit is the wrong one, only that the two cannot both stay.
6. Ask for a hint. Stuck? Hint fills in one square that is still empty or wrong and tells you which row and column it was. Show solution reveals the whole board.
7. Play another. When you finish, New sudoku deals another board at the same level; Today's sudoku brings you back to the board of the day.

The daily boards change at midnight Eastern Time, and everyone who opens the page that day gets the same puzzle, so you can compare times with a friend or a family member who plays too.

Sudoku levels: easy, medium and hard

The difference between the levels is mostly how many squares are filled in at the start. The fewer the givens, the fewer "free" deductions you get and the longer the chains of logic you need.

The times are rough guides, not targets. Everyone starts slow, and a board that takes 25 minutes in your first week often takes 10 a month later. If a level feels frustrating, drop down one step for a few days; the techniques you practice on easier boards are exactly the ones the harder boards need.

How to solve sudoku: techniques from beginner to advanced

1. Scanning: the first pass

Pick a digit, say 5, and look at every 5 already on the board. Each one rules out its row, its column and its box. If, inside one 3 × 3 box, only one square is left where a 5 could go, write it in. Then repeat for 1, 2, 3 and so on. On an easy sudoku, scanning alone often solves half the board.

2. The last empty square

Look for a row, column or box with only one or two empty squares. If eight digits are already there, the missing ninth is obvious. This sounds trivial, but players who are concentrating on harder deductions miss it all the time.

3. Naked singles

Take one empty square and check which digits its row, column and box already contain. If eight of the nine digits are used, the square has only one possible value. This is the core move of every medium sudoku.

4. Candidates (pencil marks)

When scanning stops working, list the possible digits for each empty square. In a paper puzzle these are small pencil marks in the corners; online you can keep them in your head for a row or a box at a time, or jot the tricky ones on a scrap of paper. Candidates turn a hard board from guesswork into bookkeeping.

5. Hidden singles

Sometimes a square has several candidates, yet one of those digits fits nowhere else in its row, column or box. That digit must go there. Hidden singles are the most common breakthrough on medium and hard boards.

6. Pairs and pointing

If two squares in the same row can only hold the same two digits, for example 3 and 7, then no other square in that row can be 3 or 7. That is a naked pair. Similarly, if all the possible spots for a digit inside a box sit on one row, that digit cannot appear elsewhere on that row outside the box. These eliminations are what unlock hard sudoku.

7. X-wing and beyond

Advanced solvers look for patterns across the whole grid. In an X-wing, a digit has exactly two possible spots in each of two rows, and those spots share the same two columns; the digit can then be removed from every other square in those columns. You do not need X-wing to enjoy sudoku, but learning it is a satisfying step once the hard level starts to feel routine.

Sudoku tips that save time

• Start where the board is crowded. Rows, columns and boxes with the most givens give the fastest deductions.
• Work one digit at a time. Sweeping the whole board for 1s, then 2s, finds more than jumping around.
• Never guess on easy or medium. Those boards always have a logical next step somewhere; if you cannot see it, scan again.
• Use red as a signal, not a verdict. When two squares clash, ask which of them you were less sure about.
• Take a break. A stuck board often opens up after five minutes away. Fresh eyes see the single you walked past.
• Use Hint to learn. When you ask for a hint, look at the square it filled and work out why that digit had to go there.

Sudoku for kids: 4 × 4 and 6 × 6 with pictures

The two small boards under the main game are made for children. The 4 × 4 board uses four pictures and four 2 × 2 boxes, so a six-year-old can learn the idea of "each picture once in every row, column and box" in a couple of minutes. The 6 × 6 board uses six pictures and 2 × 3 boxes and is a good bridge to the full 9 × 9 game. Pictures instead of numbers help kids see that sudoku is about logic, not arithmetic. Each small board changes daily too, and New sudoku deals another one.

If your child likes word games as well, try our crossword puzzles for kids, with short, friendly clues and a new puzzle every day.

Where sudoku came from

The puzzle we now call sudoku was first published in the United States: Dell Magazines printed it in 1979 under the name Number Place, and the puzzles are credited to Howard Garns. In 1984 the Japanese publisher Nikoli introduced it in Japan, and Nikoli's founder Maki Kaji gave it the name sudoku. The puzzle came back to the English-speaking world in 2004, when The Times in London began printing it, and within a year it had spread to newspapers across the US. Read the full story in our article Who invented sudoku?

Is sudoku good for your brain?

Sudoku keeps you focused, exercises working memory and rewards patience, and many people find it relaxing. Research on whether puzzles protect memory in the long run is more mixed than the headlines suggest. We looked at what the studies actually show in Are crosswords and sudoku good for your brain? The short version: puzzles are a pleasant, healthy habit, and they work best alongside sleep, exercise and time with other people.

More puzzles on 77.today

Play our free daily crossword, a new American-style puzzle every day with clues written by our editors, or warm up with the easy sudoku and work your way up to the hard sudoku. The 77.today home page also shows the daily puzzle in the Now column, taking turns between the crossword and the sudoku.