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How to Print Expert Sudoku on A4 Paper
A4 measures 210 × 297 mm and is the international ISO standard used across Europe, the UK, Asia, and Australia. Print 6 puzzles per page comfortably on A4. Set the paper size to A4 in the generator, print at 100% scale rather than Fit to page, and the cells come out at the size they were designed for. Every puzzle has a guaranteed unique solution.
Why A4
Why Print Expert Sudoku on A4?
A4 is the international ISO standard used across Europe, the UK, Asia, and Australia — choose this size when printing on local stationery, or to fit standard binders and folders. Dimensions: 210 × 297 mm.
Print 6 puzzles per page comfortably on A4.
About this puzzle
About Expert Sudoku
Expert Sudoku puzzles contain only 20 to 24 given clues and require the full arsenal of advanced techniques including colouring, chains, and AIC (Alternating Inference Chains). Designed for seasoned solvers.
Grid: 9×9. Clue count: 20–24.
Read the full expert sudoku guide or open the live generator.
How to solve
How to Solve Expert Sudoku — Quick Walkthrough
After candidate notation, try colouring on a single digit. Find a cell where the digit appears as a candidate. Mark it colour A. Trace through bilocal links (units where the digit has only two candidates) — alternating colours A and B. If two cells of colour A end up in the same unit, the digit must be colour B in those cells. Eliminate accordingly.
Pro tips
Tips for Expert Sudoku Solvers
- Master colouring before chain-based techniques. Use two colours to mark cells where a candidate must be one or the other. Two cells of the same colour in the same unit eliminate that candidate.
- Expert Sudoku requires complete candidate notation. The chains depend on accurate candidates — one missed elimination breaks the chain.
- X-Chains follow a single digit through the grid. Find a chain where the digit alternates between 'on' and 'off' states across cells linked by strong (only-two-candidate) relationships.
- AIC (Alternating Inference Chains) generalise X-Chains across multiple digits. Each link alternates between strong and weak inferences.
- If a chain technique would take more than 10 minutes to find, the puzzle likely has an easier path. Re-scan basic candidates before committing to deep chain analysis.
Different size?
Other Paper Sizes
Other difficulties
A4 in Other Difficulties
Want a different difficulty on A4 paper? Easy Sudoku — A4 · Medium Sudoku — A4 · Hard Sudoku — A4 · Classic Sudoku — A4 · Mini Sudoku — A4 · Kids Sudoku — A4 · Large Print Sudoku — A4.
FAQ
Expert Sudoku — A4 — Common Questions
How long does Expert Sudoku take to solve?
Expert Sudoku takes 40 to 60 minutes for skilled solvers and 90+ minutes for those new to expert-level techniques. World-class solvers can complete Expert puzzles in 8 to 12 minutes, but expect significantly longer sessions when learning.
What techniques are unique to Expert Sudoku?
Expert Sudoku introduces colouring, X-Chains, AIC (Alternating Inference Chains), forcing chains, and almost-locked sets. These techniques follow chains of logical implication through the grid to eliminate candidates that simpler techniques cannot.
Are Expert puzzles still solvable purely by logic?
Yes. Expert Sudoku puzzles still have a single solution reachable through pure logical deduction. They never require guessing — but they require recognising chain-based patterns that take significant practice to internalise.