Expert Sudoku

Your expert Sudoku stats

Finished expert puzzles are recorded in your browser (your last 25 games), so you can watch yourself improve. Nothing leaves your device.

See every level, your streaks and your recent games on the Sudoku stats page.

How difficult is Expert Sudoku?

Expert Sudoku gives you as few as 23 of the 81 cells to start, leaving around 58 empty cells. With so few clues, many cells have three or four candidates for a long time, and the progress that does happen comes from eliminating candidates, not from spotting obvious placements.

This is the level where advanced patterns appear: box-line reduction, X-Wing and linked-cell patterns such as XY-Wing. Even so, every puzzle has exactly one solution and can be solved by logic.

Times vary a lot from player to player; treat them as a rough guide, not a target. For a deeper comparison, see Sudoku strategies for every level.

How Expert Sudoku works

The rules are unchanged (see Sudoku rules), but solving is a methodical process:

1. Take every easy step first. Naked singles, hidden singles and basic scanning will still carry you a short way.
2. Write complete, accurate notes. Every empty cell needs its candidates, double-checked.
3. Run the simple eliminations. Naked and hidden pairs and triples, pointing pairs and box-line reduction.
4. Search for advanced patterns. Look for X-Wing, Swordfish and XY-Wing when simple eliminations stop.
5. Go back to the start. After each elimination, check again for easy singles and simpler patterns that the new notes may have created.

If you feel forced to guess, there is a pattern still hiding in your notes.

Tips for solving Expert Sudoku

• Double-check your notes. One missing candidate can make a valid pattern look impossible, or a wrong one look right.
• Work through techniques in order. Try the cheapest patterns first and move to X-Wing and XY-Wing only when they are exhausted.
• Look at one digit at a time. For X-Wing, list every cell where one digit can still go and look for rectangles in two rows or columns.
• Use box-line reduction. If a digit's candidates in a row or column all sit in one box, remove it from the rest of that box.
• Look for two-candidate cells. They are the building blocks of XY-Wing and other chains.
• Be patient. Expert solves often take 30 minutes or more. Step away if you stop seeing new moves.

Sudoku techniques explained covers X-Wing, Swordfish, XY-Wing and box-line reduction in detail, and Sudoku strategies explains how to organize a long expert solve.

Common mistakes to avoid

• Incomplete notes. Advanced patterns only work when every candidate is recorded correctly.
• Seeing patterns that are not there. An X-Wing needs exactly two candidate cells for the digit in each of the two rows (or columns), not three.
• Jumping to advanced techniques too soon. Many stuck positions are solved by a pointing pair or hidden single you skipped.
• Guessing. It is tempting when notes are crowded, but a wrong guess on an expert grid is very costly.
• Playing tired. Mistakes in notes multiply late in a long solve. Take a break instead.

Hints, notes, timer and other tools

Everything in the game above is free and available at every level:

• Hints: three per game. A hint fills in one correct cell. Press H as a shortcut.
• Notes: pencil notes are required on expert puzzles. Keep them complete and accurate, and update them after every placement. Press N to toggle.
• Undo and erase: take back any move as many times as you like with Undo or Ctrl+Z.
• Timer: your solving time is shown above the board. Select it or press Pause to stop the clock while you take a break.
• Mistake counting: switch it on to end the game after three wrong numbers, a good challenge once you are comfortable.
• New puzzle: press New Puzzle for a fresh expert grid whenever you like.
• Autosave: close the tab mid-game and your puzzle is waiting when you come back.
• Keyboard: arrow keys to move, 1–9 to enter a number, Backspace to erase.

Prefer to check a puzzle from a newspaper or book? The Sudoku solver solves any grid you type in.

Print expert Sudoku

Like solving with a pencil? Generate a free sheet of expert Sudoku puzzles on our printable Sudoku page, choose the layout and paper size, and print or save it as a PDF.

Ready for another level?

Mastered the expert level? Revisit the earlier levels for speed runs, or try a different kind of grid:

Want a fresh puzzle everyone plays? Try the Daily Sudoku, or switch grids with Sudoku variants such as 12×12, 16×16 and Killer Sudoku.