How to play Sudoku
Play Sudoku online at four levels: easy, medium, hard and expert. Every puzzle is new and checked to have exactly one solution. Fill cells with the keypad or your keyboard, take notes, undo and ask for a hint; repeated digits turn red. A timer and your best time per level. Free, no ads.
- Controls
- Select a cell and tap a digit on the keypad; on a computer, type 1–9, move with the arrow keys and delete with Backspace; switch notes on and off
- Features
- Puzzles with exactly one solution; clashing digits in red and the same digit, row, column and box highlighted; notes, undo and hints; your time and best time per level, and the current puzzle kept on your device
- Processing
- Runs in your browser, the computer player included; nothing is uploaded
- Choose a level and press “New puzzle”. Easy and medium need only basic deduction; hard and expert need more.
- Select an empty cell and choose a digit; with notes on, a digit goes in as a small candidate. On a computer, type the digits and move with the arrow keys.
- Fill every row, column and 3×3 box with 1 to 9 once each. Repeated digits turn red; when stuck, a hint fills one correct digit.
FAQ
Does every puzzle have one solution?
Yes. As a puzzle is made, a solver checks that each removed digit leaves exactly one solution; if not, the digit goes back.
What is the difference between the levels?
Easy has about 40 givens and medium about 32; both can be solved with naked and hidden singles alone. Hard has about 28 and cannot be solved with singles alone; expert has the fewest, about 24.
What does a hint do?
It fills the correct digit in the selected cell (or in an empty cell when none is selected) and counts the hints you used.
How do notes work?
With notes on, a digit is added to the cell as a small candidate, and choosing it again removes it. Entering a digit clears the same candidate from its row, column and box.
Is my progress saved?
The current puzzle is kept in this browser, so you can reload the page and carry on; clearing the browser’s data removes it.