Jigsaw sudoku puzzles
Jigsaw sudoku keeps everything you know from sudoku, except the boxes: instead of nine neat squares, the grid is cut into nine irregular shapes. Rows, columns and shapes each hold 1 to 9 once. The new shapes open up tricks, like the law of leftovers, that regular sudoku never needs.
Play unlimited jigsaw sudoku free online, with pencil notes and undo. For more variants, try killer sudoku or calcudoku.
How jigsaw sudoku works
Jigsaw sudoku, also called irregular sudoku, keeps the rows and columns of classic sudoku but replaces the nine 3×3 boxes with nine irregular regions of nine cells. Each region must still contain the digits 1 to 9 once. Because the regions have odd shapes, the familiar box patterns disappear and you have to look at the grid in a new way.
The law of leftovers
The most useful jigsaw technique comes from counting. Take a band of rows, for example the top three rows. Together they contain every digit three times. If some regions poke out of the band and other regions poke into it, the cells that stick out and the cells that stick in must hold exactly the same set of digits. Comparing the two groups often fixes digits that would otherwise take a long time to find.
Tips for irregular regions
- Watch long, thin regions. A region that spans many rows or columns interacts with more lines, which gives more eliminations.
- Classic techniques still work. Singles, pairs and pointing pairs all apply; just use the regions instead of boxes.
- Trace region borders carefully. Most jigsaw mistakes come from misreading which region a cell belongs to.
How to play here
Tap a cell and type a digit, or use the number pad on a phone. Right-click for pencil marks on a computer, or use Mark mode on a phone. For another variant, try Killer Sudoku.
How to play Jigsaw Sudoku
- Fill every empty cell with a digit from 1 to 9.
- Every row and every column contains each digit exactly once.
- The grid is divided into nine jigsaw shapes of nine cells. Each shape also contains each digit once.
- Choose Basic or Advanced in the Size & level menu.
Jigsaw Sudoku tips
Use the law of leftovers
Add up whole rows and compare them with the shapes inside them. Cells of a shape that stick out of the rows must match the cells of other shapes that stick in.
Watch the odd-shaped pieces
Long, thin shapes cross many rows and columns, so they get restricted quickly. They often give the first placements.
Classic techniques still work
Singles, pairs and pointing pairs work exactly as in normal sudoku. Only the shape of the boxes has changed.
Frequently asked questions
What is jigsaw sudoku?
Jigsaw sudoku, also called irregular sudoku or squiggly sudoku, replaces the nine 3×3 boxes with nine irregular shapes. The rules are otherwise the same.
Is jigsaw sudoku harder than normal sudoku?
It feels harder at first because the shapes are less familiar, but the same logic applies. Start with Basic before trying Advanced.
Does each puzzle have one solution?
Yes. Every puzzle has one solution you can reach by logic.
