The best Sudoku hints preserve the part of the puzzle you can still solve yourself. Instead of revealing an arbitrary digit, they identify a useful technique, digit or region and explain the constraint that makes the next move logical.
What is a useful Sudoku hint?
A useful Sudoku hint identifies the next logical step without revealing the whole solution. It should first name the technique or area to inspect, then narrow the search to a digit or candidate pattern, and reveal the exact placement only if needed. This lets you continue solving, understand why the move works and avoid blind guessing.
How can a Sudoku hint help without giving away the answer?
A progressive hint separates guidance into levels. You choose how much help to reveal, stopping as soon as you can finish the deduction. The first level may say “look for a hidden single in column 7.” A stronger level may identify the digit. Only the final level names the exact cell.
This is different from an answer-only hint, which reads a value from the completed solution and inserts it into the grid. The value may be correct, but it does not show the reasoning available from the puzzle’s current state.
What are the best levels for progressive Sudoku hints?
| Hint level | What the hint reveals | What you still determine |
|---|---|---|
| 1. Technique | The solving method to use | Digit, region and move |
| 2. Focus | The row, column, box or digit involved | Exact candidate relationship |
| 3. Logic | Why candidates can be removed | Final placement or elimination |
| 4. Move | The exact cell and value | The rest of the puzzle |
Start with the smallest hint. If “look for a naked single” is enough, there is no reason to reveal a coordinate. If it is not enough, move to the focus and logic levels before requesting the move.
The most useful Sudoku hint restores a broken reasoning chain. It does not replace that chain with a digit from the answer key.
What does an explanatory Sudoku hint look like?
The examples below are miniature candidate situations. They show the form a good hint should take; they are not taken from a hidden finished grid.
Example 1: a naked single
Suppose row 5, column 5 has the candidates {3} after the digits already present in its row, column and 3×3 box are excluded.
- Technique hint: Look for a cell with only one candidate.
- Focus hint: Inspect the center box.
- Explanation: Row 5, column 5 has no legal candidate except 3.
- Move: Place 3 at row 5, column 5.
The explanation matters because “put 3 in the center” alone does not tell you whether the move came from logic or from the solution.
Example 2: a hidden single
Suppose several cells in row 6 contain multiple candidates, but the digit 7 appears as a candidate in only one of those cells: row 6, column 8.
- Technique hint: There is a hidden single in one row.
- Focus hint: Check where 7 can appear in row 6.
- Explanation: Every other cell in row 6 is blocked from containing 7.
- Move: Place 7 at row 6, column 8.
The cell can have other pencilled candidates and still be a hidden single because the deduction asks where 7 can go within the row.
Example 3: locked candidates
Suppose every candidate 4 inside the top-middle box lies on row 2. One of those box cells must therefore contain 4, so cells elsewhere on row 2 cannot contain 4.
- Technique hint: Look for a candidate locked to one line inside a box.
- Focus hint: Compare candidate 4 in the top-middle box with row 2.
- Explanation: The box must place 4 on row 2, so 4 can be removed from row 2 outside that box.
- Move: Remove candidate 4 from the affected cells elsewhere on row 2.
This kind of hint teaches a reusable pattern instead of exposing one finished value.
Free tool / Paper Sudoku
Need a Sudoku hint from a newspaper or book?
Take or upload a photo with the Sudoku Solver, review the recognized digits, and choose “Give me one hint.” The tool evaluates the editable grid and returns a logical next move. You can still request the full solution, but the hint option is designed to help you continue the puzzle yourself.
Get a hint from your Sudoku photo →What should you check when you are stuck on Sudoku?
Check the puzzle in this order before revealing a value:
- Verify every entered digit. One transcription or typing error can create a false contradiction.
- Update candidates. Remove candidates eliminated by recent placements.
- Scan for naked singles. Find cells with one remaining legal value.
- Scan for hidden singles. Check whether a digit has only one possible cell in a row, column or box.
- Compare boxes with crossing lines. Look for locked candidates.
- Inspect pairs and triples. A restricted set can remove candidates from the rest of a unit.
- Change your scanning direction. Switch from boxes to columns or follow one digit across the whole grid.
- Request a progressive hint. Ask for the technique or region before the exact move.
If the puzzle still appears impossible, recheck the givens before assuming an advanced technique is required. A misplaced digit can make every valid strategy fail.
Can hard Sudoku be solved without guessing?
Yes. A properly constructed Sudoku with one intended solution can be solved through logical deductions, although a hard puzzle may require techniques beyond singles and locked candidates. Guessing may produce an answer, but it hides the deduction that distinguishes one candidate from another. When learning, request a technique-level hint before trying speculative branches.
Which Sudoku solving technique should a hint name?
The technique depends on the current grid. Common hint labels include:
- naked single;
- hidden single;
- locked candidates or box-line reduction;
- naked or hidden pair;
- naked or hidden triple;
- X-Wing;
- XY-Wing;
- candidate coloring or chains.
A hint system should not claim the most advanced available technique merely because it can detect one. It should prefer a clear, locally verifiable deduction when a simpler move exists.
Our game / Real hints
How are Detective Sudoku hints different?
Detective Sudoku is not classic 9×9 Sudoku. It replaces digits and boxes with suspects, rooms and truthful spatial clues while retaining one suspect per row and column. Its real hints do not give you the answer or solution: they identify the clue responsible for the next deduction and explain why a suspect must—or cannot—occupy a position.
See how real hints work in Detective Sudoku →Frequently asked questions about Sudoku hints
How do I get a Sudoku hint for one cell?
Enter the current grid into a solver that explains its reasoning, then request one hint rather than the complete solution. Confirm the givens first so the recommended value is based on the same puzzle you are solving.
Can I get a Sudoku hint from a photo?
Yes. A photo-based Sudoku tool can transcribe a printed grid from a newspaper, magazine or book. Review every recognized digit before asking for a hint because shadows, page curvature and faint printing can cause transcription errors.
What is the easiest Sudoku hint to check first?
Check for naked singles first: cells with only one legal candidate. Then look for hidden singles, where one digit has only one possible position in a row, column or box.
Why does a Sudoku app give a correct digit without an explanation?
Some solvers know the completed grid but do not maintain a human-readable deduction path. They can reveal a correct value without identifying the technique that proves it from the current candidates.
Should a Sudoku hint reveal the solution?
Only when the player explicitly requests it. A learning-oriented hint should begin with the technique or area, provide the logical relationship next, and reserve the exact value for the final level.