Play Free Sudoku Online: Tips for Every Level
Plenty of Sudoku apps interrupt every couple of puzzles with a video ad. Sudoku keeps it simple: fresh puzzles at four levels, pencil-mark notes, hints when you're stuck, and your game saved if you close the tab.
Steps
- Choose Easy, Medium, Hard or Expert and press New game.
- Tap a cell, then a number. Turn on Notes to pencil in small candidate numbers.
- Use Hint or Check if you're stuck. Finish the grid to see your time.
On a keyboard: arrow keys to move, 1–9 to fill, Backspace to clear, N to toggle notes.
The rules
Fill the 9×9 grid so every row, every column and every 3×3 box contains the digits 1 to 9 exactly once. That's it. No arithmetic is involved; the digits could just as well be letters.
Fair puzzles
Every puzzle is generated fresh and checked by a solver, so it has exactly one solution reachable by logic. That matters: badly made puzzles force you to guess, which isn't Sudoku, it's coin-flipping. Harder levels simply give fewer starting numbers and require more advanced reasoning.
Helpful features, used well
Notes track candidate digits per cell and clear themselves when you place a digit in the same row, column or box. That automatic cleanup removes the tedious part of pencil-marking.
Highlighting shows the selected cell's row, column, box and matching digits. Tap a 7 and every 7 on the board lights up, which makes spotting where 7 can still go almost instant.
Hints and Check are there for when you're truly stuck. Try to use Check sparingly: it's more satisfying, and you learn more, when you find your own mistake.
Techniques that get you unstuck
- Scanning. Pick a digit and look at each box: where can it go, given the rows and columns that already contain it? Easy puzzles fall to this alone.
- Naked singles. A cell with only one possible candidate.
- Hidden singles. A digit that can only go in one cell of a row, column or box, even if that cell has other candidates.
- Pairs. If two cells in a row can only be 3 or 8, no other cell in that row can be 3 or 8. Eliminate them.
- Pointing. If all the 5s for a box lie in one row, 5 can't appear elsewhere in that row outside the box.
Hard and Expert levels need pairs, pointing and sometimes more advanced patterns. Notes make them visible.
Solving a newspaper puzzle
Stuck on yesterday's newspaper Sudoku? Choose Enter your own, type the given numbers, and press Solve. You can also play it here with hints instead of jumping straight to the answer.
Why bother
Short sessions of logic puzzles are a pleasant break from screens full of feeds. Sudoku is also a good one to share with kids learning to reason step by step, and with older relatives who enjoy the newspaper puzzles but find the print too small.
A gentle routine
If you're new, play Easy until you can finish without hints, then move up a level. Time yourself only after the method feels natural; speed comes from recognising patterns, not rushing.
Privacy
According to the page, everything runs on your device and your game is saved in this browser. Google ads appear on the page, as across the site.
FAQ
Does every puzzle have one solution? Yes, each is checked by a solver first.
Can I use a keyboard? Yes: arrows, 1–9, Backspace, N for notes.
Can I solve a puzzle from a newspaper? Yes, with Enter your own.
Is my game saved? Yes, in this browser.
Fancy a puzzle? Start one on Sudoku.
— Alok Kumar Singh