Number puzzle
Sudoku
One through nine, once per row, column, and box. Never guess.
A hint was used. The time for this grid won't be saved as a best score.
One puzzle a day, the same for everyone
The day's grid is Medium level, drawn from the date. It's generated and then emptied cell by cell as long as a solver confirms that only one solution remains: never two, never none.
- The same grid for everyone, until midnight in your device's time zone.
- The challenge clock starts on your first digit.
- A hint fills one cell but doesn't record the challenge. The note under the grid reminds you.
- Completing a challenge, any of the four, extends your streak by one day.
The Free play / Daily challenge toggle sits at the very top of the board. The challenge never touches your free-play best scores, and free play stays unlimited.
Five steps to your first win
- Pick an empty cell.Click it: it highlights. The darker cells are the starting clues and don't change.
- Look for the only possible value.A digit already present in the cell's row, column, or box is off-limits.
- Place the digit.On the pad below the grid, or straight from the keyboard. A conflicting digit shows in black with a border.
- Work outward step by step.Every digit you place constrains others. Start with the fullest rows and boxes.
- Fill the whole grid.The win is recognized as soon as all 81 cells are correct. A “Hint” button unsticks you if needed.
What you need to understand
One input for every way to play
Mouse and trackpad
Click an empty cell to select it, then a digit on the pad below the grid. The ✕ key clears the selected cell.
Touchscreen
The number pad sits below the grid, with large keys. A conflicting cell gets a black border without erasing anything.
Keyboard
Cells are in the tab order. A digit from 1 to 9 fills the cell; Backspace or 0 clears it. The starting clues are locked.
Five things worth knowing
- A cell whose row, column, and box leave only one possible digit can be filled without risk. Look for those first.
- Conversely, look for a digit that has only one possible spot left in a box: that's the other half of the method.
- No grid on this site has two solutions. If you're torn between two digits for a cell, one of them creates a conflict elsewhere.
- A digit shown in black with a border is in direct conflict with a twin in its row, column, or box. It doesn't say which one is right.
- The level is set by the number of clues given: forty on Easy, around thirty on Medium, fewer than thirty on Hard. The logic stays the same.
Sudoku, in detail
Fill the 9 by 9 grid with the digits 1 through 9 so that every row, every column, and each of the nine 3 by 3 boxes contains all nine digits exactly once.
No. Every grid is generated and then emptied cell by cell as long as a solver confirms that only one solution remains. So there's always a purely logical path, with no assumptions, all the way to the end.
By the number of clues given at the start: about forty on Easy, around thirty on Medium, fewer than thirty on Hard. The fewer the clues, the longer the deduction, but it always remains possible.
That it's in direct conflict with an identical digit in its row, column, or box. The border doesn't say which of the two is wrong, only that they can't coexist.
It fills one cell with its final value, the one from the solution. In exchange, the time for that grid isn't saved as a best score, and a note under the grid reminds you.
Those are the starting clues, the ones that make the grid determined. Changing them would mean playing a different grid. They're darker and announced as such to screen readers.
The idea comes from the American “Number Place” of the 1970s; it was popularized in Japan under the name sudoku by the publisher Nikoli, then around the world. The puzzle itself is in the public domain; our grids are generated by our code.
The day's grid, at Medium level, is drawn from the date and verified to have a unique solution before it's shown. It's the same for everyone until midnight. Using a hint finishes the grid but doesn't record the challenge.
Keep exploring the site
All four games play right on the page, with no account and no download.