Medium Sudoku
What a medium Sudoku asks of you
Medium puzzles start with 30 to 35 givens and cannot be finished with singles alone. At least once in every grid you have to remove candidates with a pattern before the next single appears. The patterns at this level are naked pairs, hidden pairs, pointing and claiming. Nothing harder is ever required, so a medium puzzle rewards patience rather than advanced theory.
| Medium level | Value |
|---|---|
| Techniques needed | Singles + naked/hidden pair, pointing, claiming |
| Givens | 30–35 |
| Solutions | Exactly one |
| Notes needed | Yes, for at least one step |
The first time a medium grid stops you
In one grid from the medium collection (32 givens), the engine places 29 digits in a row using singles alone. Then it hits a wall: 20 empty cells and 45 candidates remain, and no digit can be placed. This is the first step that has to erase candidates instead of placing a digit.
The key was the 6 in box 4 (rows 4 to 6, columns 1 to 3). Inside that box the 6 can only go in two cells, both in row 5: row 5, column 1 (r5c1) and row 5, column 3 (r5c3). So the 6 of row 5 belongs to this box, and the engine removes 6 from row 5, column 4 and row 5, column 5. That is a pointing pattern, and it erased just two candidates. It was enough: column 4 was left with a single place for its 6 (row 4, column 4), and the very next step filled it in. The remaining 20 steps were singles again, and the grid finished in 50 steps: 49 digits and one pointing.
Strategies for medium puzzles
1. Start with singles, then switch to notes
The opening of a medium grid usually flows like an easy one. When scanning stops producing digits, fill in the candidates of the emptiest box or row. The pair or pointing pattern you need is usually hiding where the board is most open.
2. Hunt for two cells with the same two candidates
If two cells in a row each allow only 4 and 9, those two digits are locked into those two cells. Every other cell in the row can lose its 4 and 9. That is a naked pair, and it often unlocks a single straight away.
3. Use boxes to point along lines
Inside a box, if every possible place for a 5 lies on the same row, then the 5 of that row must be in this box. You can remove 5 from the rest of the row. Claiming is the mirror image: a row whose only 5s sit inside one box clears the 5 from the rest of that box.
4. Check hidden pairs when a line looks crowded with notes
Sometimes two digits can only go in the same two cells of a unit, even though those cells hold other candidates too. Those cells are reserved for the pair, so you can erase their other notes.
5. Keep notes tidy
Automatic note clearing removes a placed digit from its row, column and box. Leave it on at this level: stale notes are the most common reason a medium puzzle seems impossible.
Moving up from medium
When you can spot a pointing pattern without writing every note, you are ready for hard puzzles. They add triples and the X-Wing, both of which grow directly out of the pair and line ideas you practice here.
Medium Sudoku questions
- What is the difference between easy and medium Sudoku?
- Easy puzzles can be solved with singles alone. Medium puzzles need at least one candidate-elimination step, such as a pair or a pointing pattern, before the solution can continue.
- How long does a medium Sudoku take?
- Typically 8 to 20 minutes. The first time you need a pair it may take longer, but the pattern quickly becomes familiar.
- I am stuck on a medium puzzle. What should I check?
- Fill in all candidates for one box, then look for two cells sharing the same two candidates, or a digit whose candidates in a box all lie on one line. A hint will also name the exact technique you need.
- Is the Daily Sudoku medium every day?
- No. The daily puzzle is medium on Wednesdays and Thursdays. It is easy at the start of the week, hard on Friday and Saturday, and expert on Sunday.