PuzzleDayHow to play sudoku
Fill the 9×9 grid so that every row, every column and every one of the nine 3×3 boxes contains each digit from 1 to 9 exactly once. Some digits are given at the start; your job is to work out the rest by logic alone. No maths is involved — the digits could just as well be letters or colors.
- Tap a cell (or move with the arrow keys).
- Tap a digit on the pad, or type it. Tap the same digit again to clear it.
- Use Notes to pencil in possible digits when you are not sure yet.
- The puzzle is solved when every cell is correct — the board ripples and your time is saved.
Beginner techniques
Scanning (hidden singles)
Pick a digit — say 5 — and look at one box. Cross out every row and column in that box that already has a 5 elsewhere. If only one empty cell in the box is left, the 5 must go there. Scanning each digit through each box solves most easy puzzles.
Last free cell (naked singles)
Look at a single cell and list the digits already used in its row, column and box. If eight different digits are used, the ninth is the answer. The number pad helps here: the small count under each digit shows how many of it are still left to place.
Pairs
If two cells in the same row, column or box can only hold the same two digits (for example 3 and 7), those two digits are “taken” — you can remove 3 and 7 from the notes of every other cell in that unit. This is the key technique for hard and expert puzzles.
Using the tools fairly
- Show mistakes colors wrong digits red. Turn it off for a pure challenge.
- Hint fills in the selected cell (or a random one). Games solved with hints don’t count toward your best time.
- Undo steps back one move at a time, including note changes.
- The timer pauses automatically when you switch tabs, and you can pause it yourself with the clock button.
Choose your level
New to sudoku? Start with easy sudoku. Ready for more? Try hard or the brutal expert sudoku. Prefer words? Play today’s daily word game.
Frequently asked questions
When does the daily sudoku change?
At midnight in your time zone. Each difficulty level has its own daily puzzle, numbered from our launch day, and everyone gets the same grid — so you can compare times with friends.
Does every puzzle have one solution?
Yes. Every puzzle is checked by a solver as it is made, and a clue is only removed if the grid still has exactly one solution. You never need to guess.
What do the difficulty levels mean?
They mostly reflect how many clues you start with: about 40 for easy, 32 for medium, 27 for hard and 24 for expert. Fewer clues means longer chains of reasoning before each new digit appears.
How do notes work?
Turn on Notes (or press N) and tap digits to pencil in candidates for the selected cell. When you place a digit, it is automatically removed from the notes of every cell in the same row, column and box.
Is my game saved?
Yes. Your progress, time and notes are saved in your browser automatically, so you can close the tab and finish later on the same device.
Can I use the keyboard?
Yes: arrow keys to move, 1–9 to enter a digit, Backspace or 0 to erase, N for notes, P to pause and Ctrl+Z (or ⌘Z) to undo.