Sudoku Variants: What Kinds of Sudoku Are There?

Types of sudoku at a glance

Classic sudoku (9×9)

A classic sudoku has 81 squares in 9 rows and 9 columns, split into nine boxes of 3 × 3 squares. Each digit from 1 to 9 appears exactly once in every row, every column and every box. Every variant on this page takes that rule as its starting point. For a step-by-step walk-through, see our sudoku rules.

Mini sudoku: 6×6 and 4×4

Mini sudoku is the name for the small grids. A 6×6 sudoku has 36 squares and six boxes that are 2 squares tall and 3 wide, filled with the digits 1 to 6. A 4×4 sudoku has 16 squares and four boxes of 2 × 2, filled with the digits 1 to 4. The rule stays the same; only the grid shrinks. That makes mini sudoku a good way to learn, and a nice fit for a short break.

Rules, tips and a worked example for the small grid are in our 6×6 sudoku guide.

Killer sudoku

In killer sudoku, the grid is also divided into cages: groups of squares with a dotted outline and a small number in the corner. That number is the sum of the digits in the cage, and no digit repeats within a cage. The normal sudoku rules still apply. Often, not a single digit is given at the start.

Some cages give away their contents right away. Two squares that add up to 3 can only hold 1 and 2, two squares that add up to 17 only 8 and 9, and three squares that add up to 6 only 1, 2 and 3. A two-square cage with a sum of 10, on the other hand, has four options: 1 + 9, 2 + 8, 3 + 7 and 4 + 6. 5 + 5 is out, because no digit can repeat in a cage.

Here’s a second approach: every row, column and box contains the digits 1 to 9, so it always adds up to 45. If you know the sum of some squares in a box, say from cages that lie entirely inside it, you also know the sum of the rest. If only one square is left, its digit is fixed. So killer sudoku does involve a bit of arithmetic, but only small sums.

Diagonal sudoku

Diagonal sudoku, also called sudoku X, adds one rule: the two long diagonals from corner to corner must each contain every digit from 1 to 9 exactly once. The center square belongs to both diagonals. That gives you a fourth kind of area to check when you rule out digits.

Jigsaw sudoku: irregular boxes

In jigsaw sudoku, the boxes aren’t squares but irregularly shaped regions. On a 9×9 grid, each region is made of nine connected squares. Otherwise, the usual rule applies: each digit appears exactly once in every row, every column and every region. Because the regions interlock, you’ll need to follow the thick lines closely.

Samurai sudoku

A samurai sudoku is made of five 9×9 sudokus that overlap in the shape of an X. The center grid shares each of its four corner boxes with one of the four outer grids, and the digits in a shared box count for both puzzles. That adds up to 369 squares in total. The shared boxes make good starting points, since they combine the given digits from two grids.

Murder sudoku: sudoku with a floor plan

In a murder sudoku, the number puzzle is part of a crime case. Alongside the sudoku comes a floor plan: a layout of rooms and furniture where you place the suspects. The plan follows a rule that feels a lot like sudoku: exactly one person per row and column. The suspects’ statements narrow down who was where, until it’s clear who was alone with the victim.

The appeal is in the two layers. The sudoku is a familiar task, while the floor plan calls for spatial thinking and careful reading. The full details are in our floor plan rules.

Which variant is right for you?

• For learning and short breaks: mini sudoku on a 4×4 or 6×6 grid.
• For your daily puzzle: classic 9×9 sudoku, which comes in every difficulty level.
• When 9×9 starts to feel routine: diagonal or jigsaw sudoku. Both barely touch the core rule, yet they still feel fresh.
• If you don’t mind a little arithmetic: killer sudoku.
• For a long evening: samurai sudoku, with five grids at once.
• If you love a good mystery: murder sudoku, where every solved puzzle moves the case forward.

Sudoku in a murder mystery

Sudocrime is a murder sudoku game. The practice case, “The Missing Key”, starts small: a 4×4 sudoku, a 4×4 floor plan and no murder. In “Silence at Lindenrain”, each of the six chapters has a 6×6 sudoku and a floor plan of 5×5 or 6×6 squares. If you get stuck, the hint shows you the next step in three stages. See how a case plays out in How a murder sudoku works, and pick up techniques that help in every variant in our sudoku tips.