Medium Sudoku Puzzles
Medium Sudoku sits between a warm-up and a workout. Boards start with 36 to 38 givens, about the same as Easy, but roughly half of them require a second technique: the hidden single. That means you cannot solve every cell by staring at it alone; sometimes you have to chase a digit across the grid to find the one cell where it still fits.
What changes at Medium
Individual cells stop being obvious. On an Easy board there is always a cell whose row, column and box together exclude eight digits. On a Medium board you will hit stretches where no cell is that constrained, yet the puzzle is still perfectly solvable. The way through is to switch viewpoints: instead of asking "what fits in this cell?", ask "where in this box can the 7 go?".
Medium Sudoku strategies: cross-hatching for hidden singles
Choose a digit. Draw imaginary lines through every row and column that already contains it. Any box that does not yet have the digit will have some of its cells crossed out by those lines. When exactly one cell is left uncrossed, the digit belongs there. Sweep all nine digits, then start again; each placement changes the picture for the others. Players who do this in a fixed order, 1 through 9, rarely get stuck on a Medium board.
Medium Sudoku tips
- Alternate the two questions: "what can go here?" for cells, "where can this go?" for digits.
- Focus on digits that already appear six or seven times; they have only two or three homes left.
- Notes are optional but useful once the board is half full. Write candidates only in cells with two possibilities to keep the grid readable.
- If nothing moves, check whether a recently placed digit completed a row or column you have not re-scanned.
Next steps
Comfortable with hidden singles? Hard Sudoku keeps the same techniques but cuts the givens to 30. If you want to go back and speed up your scanning first, Easy Sudoku is one click away. All the techniques mentioned here are explained in the Sudoku techniques guide.
Frequently asked questions
How is Medium different from Easy?
The number of givens is similar (36 to 38), but about half of Medium boards require hidden singles: finding the only cell in a row, column or box where a digit can still go, rather than the only digit that fits a cell.
Should I use notes on Medium puzzles?
They help but are not required. Cross-hatching digit by digit solves every Medium board; notes simply make it easier to keep track once the grid is half full.
How long does a Medium Sudoku take?
It depends mostly on practice, and we do not have a reliable average to quote. Medium has 43 to 45 empty cells and needs hidden singles as well as naked ones, so the time goes on scanning, not on advanced logic. Statistics keeps your own best and average time for each level.