Printables / Puzzles
Sudoku Generator
Generate printable sudoku puzzles, easy, medium, or hard, one or four to a page, each checked to have exactly one solution, with an answer sheet.
Sudoku Generator: Each puzzle starts as a complete random grid that follows the sudoku rules. Pairs of opposite squares are then removed at random, keeping the symmetric look of published puzzles, and after every removal a solver checks that the puzzle still has exactly one solution. Removal stops at about 40 clues for easy, 32 for medium, and 26 to 29 for hard. Runs 100% locally in your browser with zero server file uploads.
- Category
- School & study tools
- Runs
- In your browser
- Cost
- Free · no sign-up
- Availability
- Ready to use
Runs entirely in your browser
Sudoku · Medium
Sudoku · Medium · Answers
Every puzzle is checked by a solver to have exactly one solution. Easy puzzles have about 40 given numbers, medium about 32, and hard about 26 to 29.
Solving strategies
Start with the easy wins: for each digit, look along the rows and columns that already contain it to find the one square in a box where it can go. Then look for squares where only one digit is possible, because every other digit already appears in that row, column, or box.
When those run out, write small candidate digits in the corners of empty squares. Patterns among the candidates, such as two squares in a row that can only hold the same two digits, let you rule digits out elsewhere.
Where sudoku comes from
The puzzle was published in the United States in 1979 as Number Place, became popular in Japan in the 1980s under the name sudoku, short for a phrase meaning the digits must remain single, and spread worldwide from 2004. For other printable puzzles, see the word search generator.
How to use it
- Choose the difficulty and how many puzzles to put on a page.
- Press New puzzle for another set.
- Print the puzzles, and print the answers separately.
Privacy & limitations
Puzzles are generated in your browser.
Related tools
Frequently asked questions
How do you play sudoku?
Fill the grid so that every row, every column, and every 3 × 3 box contains each digit from 1 to 9 exactly once. The given numbers cannot be changed; each puzzle has only one correct answer, which logic alone can find.
How are the difficulties different?
Mainly by the number of clues: fewer clues usually mean longer chains of reasoning. Easy puzzles can mostly be solved by finding the only place a digit fits; hard ones need more advanced techniques.
Why exactly one solution?
A puzzle with two solutions forces a guess at some point, which good sudoku never does. Every puzzle here is checked by a solver that looks for a second solution and rejects the puzzle if it finds one.
Can I print several puzzles at once?
Choose four per page for a compact sheet, ideal for classrooms or a travel booklet, and print the matching answer page.
Free tool · runs in your browser · no account required