Play medium sudoku online for free: a classic 9×9 sudoku with 32 numbers already filled in and 49 squares left to solve. Every puzzle in this medium sudoku game is new, has exactly one answer and can be solved by logic alone, with no guessing. Medium puzzles are the step after easy: singles still do most of the work, but you also need to hunt for the one square where a number can go. There are hints, a mistakes counter and a timer, the puzzles work on phones and tablets, and you can print more with an answer key.
Medium sudoku online: play and print
Play the medium sudoku above, then print the same level: two medium 9×9 puzzles on a page and an answer key page with the solutions in red. The pictures also show a fresh medium puzzle with 32 givens and a puzzle half solved.
How to play medium sudoku
- Fill every row, column and box: each of the nine rows, columns and 3 × 3 boxes must hold the numbers 1 to 9 once.
- Tap a square, then a number, or type it on a keyboard.
- Wrong numbers turn red and add to the mistakes counter. Erase clears a square, and Hint fills in one square for you.
- Use logic: there is only ever one solution, so no guess is needed.
Sudoku hidden single: a medium sudoku worked example
Here is a medium 9×9 sudoku with 32 numbers given. In an easy puzzle every step is a square with only one possible number, a naked single. In a medium puzzle, that supply runs out, and the next step is a hidden single: a number that has only one square left in its row, column or box. This puzzle can be finished with these two techniques alone: 39 squares fall to naked singles and 10 need a hidden single, 49 steps in all.
- Naked singles first. The first four steps are naked singles, squares where only one number is left once the row, column and box are checked.
- The first hidden single (step 5). In row 5, the number 6 is missing, and the row has 4 empty squares. Columns 2, 7 and 9 already contain a 6, so the 6 cannot go there. That leaves only row 5, column 4, so that square must be 6.
- The next ones follow. After more naked singles, row 5 needs an 8, and columns 2 and 7 already have one, so it goes in row 5, column 9. Then row 7 needs an 8 too, and columns 7, 8 and 9 are blocked, so it goes in row 7, column 6.
Each time a number goes in, the squares around it lose a candidate, which is why the grid starts to fall faster near the end. This is the finished solution:
Medium sudoku strategy: scanning for hidden singles
The best way to find a hidden single is to scan one number at a time. Pick a number, look at where it already sits, and cross out the rows, columns and boxes it blocks. The squares left in a box or row are the only places it can go. Start with the numbers that are given the most, because they block the most squares. In the example above the numbers given most often are 1, 4 and 6, with 5 each:
| Number | Times given in the example |
|---|---|
| 1 | 5 |
| 2 | 2 |
| 3 | 1 |
| 4 | 5 |
| 5 | 4 |
| 6 | 5 |
| 7 | 4 |
| 8 | 3 |
| 9 | 3 |
The number given the fewest times, the 3, is the hardest to scan for, so leave it until later and let the other numbers do the work. Our how to solve sudoku guide shows scanning with pictures.
Free sudoku techniques by level
| Level | Numbers given | Squares to solve | Main technique |
|---|---|---|---|
| Easy sudoku | 40 | 41 | Naked singles |
| Medium sudoku | 32 | 49 | Naked and hidden singles, with some pencil marks |
| Hard sudoku | 27 | 54 | Pencil marks and pairs |
If you get stuck on a medium puzzle, write the possible numbers lightly in a square, a technique called pencil marks, and look for a square with two numbers that match another square in the same row or box. Our printable sudoku maker prints medium puzzles in black and white or color, one, two or four to a page, with an optional answer key.
Printable medium sudoku puzzles with an answer key
A printable medium sudoku is handy for the car, the classroom or a quiet evening. The sheet above has two medium puzzles with 32 numbers each, and a second page with the answers in red, so you can check your work or peek at one square without spoiling the rest. Free sudoku puzzles like these also make good homework for children who have mastered easy puzzles, because each page can be done in a sitting and corrected straight away.
Medium sudoku puzzles: a short history
The modern puzzle appeared as Number Place in a Dell puzzle magazine in 1979, created by Howard Garns, an architect from Indiana, and it was named sudoku in Japan in the 1980s. Wikipedia’s Sudoku article tells the story. The popularity of medium puzzles comes from the balance: you cannot solve the grid by simply filling in squares, but you do not need advanced techniques either.
Medium sudoku tips for beginners
- Scan every number once before you look for harder moves, because each new number opens more singles.
- Work in boxes and rows: a hidden single can appear in any of the three kinds of unit.
- Say it aloud: “the 6 cannot go in these columns, so it goes here” makes a clear step.
- Use Hint rarely: it counts as a mistake, but it will unstick a hard spot.
- Take a break: coming back to a puzzle after a few minutes often shows the move you missed.
Many people who can solve easy puzzles in ten minutes need fifteen to thirty for a medium one at first, and the time falls with practice. The puzzle has no time limit, so the timer is only for fun.
Medium sudoku: frequently asked questions
What is medium sudoku?
Medium sudoku is a 9×9 puzzle with fewer numbers given than easy, 32 of 81 in this game, so that naked singles are not enough and you also need hidden singles.
How many numbers are given in a medium sudoku?
Every medium puzzle here starts with 32 numbers, and the rest are removed only while the puzzle still has exactly one solution.
What is a hidden single in sudoku?
It is a number that can go in only one square of a row, column or box, because every other square in that unit is blocked. It is the main technique for medium sudoku.
Can I print medium sudoku puzzles?
Yes. Use the printable sudoku maker to print medium puzzles with an answer key, or the two-puzzle sheet shown above.
Is the medium sudoku free, and do kids need an account?
Yes, it is free, and no account is needed. Best scores are saved only in the browser on this device.
Does it work on phones and tablets?
Yes. Every game is built for touch first and also works with a mouse on a computer.