Jigsaw Sudoku: Rules, Tips, and How to Start

Jigsaw Sudoku (also called Irregular Sudoku) feels instantly different from classic 9×9 grids. The numbers still follow the same row-and-column rules, but the familiar 3×3 boxes are replaced by winding, jigsaw-shaped regions. That one change makes the puzzle feel more visual, more spatial, and surprisingly addictive.

If you have solved a few standard Sudokus and want something fresh without learning a whole new ruleset, Jigsaw is a perfect next step.

What Is Jigsaw Sudoku?

A Jigsaw Sudoku is still a 9×9 Sudoku, but instead of nine 3×3 boxes, the grid is divided into nine irregular regions. Each region contains exactly 9 cells.

The rules are:

• Each row must contain digits 1–9 exactly once.
• Each column must contain digits 1–9 exactly once.
• Each irregular region must contain digits 1–9 exactly once.

That is it. No sums, no extra symbols, no special math — just a different map.

How Jigsaw Changes Your Solving

In classic Sudoku, you can scan a 3×3 box quickly because it is a neat square. In Jigsaw, the region “box” snakes around, so your eyes have to do a little more work.

Two quick shifts help a lot:

• Treat each region outline like a bold boundary — it is your new “box.”
• Scan by digit (all 1s, all 2s, etc.) more often than you rely on box symmetry.

A Simple Solving Flow (That Works on Most Grids)

When you are new to Jigsaw Sudoku, use a repeatable loop:

1. Fill obvious singles (cells with only one possible digit).
2. Scan one digit at a time across rows and columns to spot forced placements.
3. Work region-by-region: for each irregular region, list which digits are missing and where they could go.
4. Use overlaps: a tight region often forces a placement in a row, which then unlocks another region.
5. Repeat the loop until the grid opens up.

This approach keeps you from feeling lost when the regions look chaotic.

Three Practical Tips to Make Jigsaw Easier

1. Mark the Region “Corners” in Your Mind

Irregular regions usually have a few tight turns or narrow “necks.” Those spots are often where placements become forced first, because there are fewer ways for digits to fit without breaking row/column rules.

• If a region has only 2–3 open cells left, focus there.
• If a region has a narrow strip (like a 1×3 run), scan the intersecting rows and columns immediately.

2. Use Light Pencil Marks (But Keep Them Tidy)

Candidate notes are especially useful in Jigsaw Sudoku because region boundaries are less predictable.

• Write candidates small and consistent so you do not confuse them with placed digits.
• Re-scan candidates after every few placements — Jigsaw puzzles often “cascade” once one region cracks.

3. Slow Down When You Cross a Region Boundary

Most Jigsaw mistakes come from forgetting which cells belong to which region.

When you place a number near a boundary:

• Double-check the region outline before you commit.
• Confirm the digit does not already exist in that irregular region.

Want a Pack of Jigsaw Puzzles to Practice With?

If you want a compact set you can take anywhere, try the Pocket Jigsaw Sudoku book. For a larger variety across difficulties, browse the Jigsaw Sudoku series.

Jigsaw Sudoku is one of the most satisfying “same rules, new feeling” variants — once your eyes learn the regions, the logic clicks into place and the solves feel wonderfully fresh.