Medium Sudoku Online
Play a free medium 9x9 Sudoku puzzle, no account required. Notes, hints, undo, and auto-save help you practice logical solving.
- No sign-up
- Free to play
- Notes and hints
- Progress auto-save
Select an empty cell, then enter a number.
Find Hidden Singles
In medium Sudoku, a cell may have several candidates while a specific digit has only one possible location in a row, column, or box. Scan one digit at a time to find these hidden singles.
Learn Locked Candidates
If all candidates for a digit inside one 3x3 box sit in the same row or column, that digit can be removed from the rest of that row or column.
Understand Pointing Pairs
When two candidates in a box line up in the same row or column, the matching digit can often be excluded elsewhere in that line.
Clean Up Notes After Every Confirmed Digit
After placing a digit, remove it from candidates in the same row, column, and box. Then check whether any new single candidates appeared.
Do Not Stare at One Box Too Long
If one area stops giving clues, switch to another digit or another region of the board. Medium puzzles often open up after a fresh scan.
Medium Sudoku FAQ
Do I need notes for medium Sudoku?
Usually, yes. Start with cells that are narrowed to two or three candidates so the board stays readable.
What is the difference between a single candidate and a hidden single?
A single candidate means one cell has only one possible digit. A hidden single means one digit has only one possible cell within a row, column, or box.
Which guide should I read next?
The Sudoku strategy guide explains single candidates, hidden singles, and note cleanup in order.