Sudoku Variants: 4×4 to 16×16

Which Sudoku size should you play?

How Sudoku variants work

Every size on this page follows the exact same rule as classic Sudoku: fill the grid so that every row, every column and every box contains each symbol exactly once. Only two things change from one size to the next — how many symbols there are, and the shape of the boxes.

4×4 and 9×9 use square boxes (2×2 and 3×3), because their size has a whole-number square root. 6×6 and 12×12 don't, so their boxes are rectangles instead — 6×6 splits into six boxes that are 3 columns wide and 2 rows tall, and 12×12 into twelve boxes 4 columns wide and 3 rows tall. 16×16 goes back to square 4×4 boxes, and needs more symbols than digits alone provide, so it uses 1–9 followed by the letters A through G.

Because the underlying rule never changes, every strategy from our how to play Sudoku guide — naked singles, hidden singles, pointing pairs and the rest — applies exactly the same way here, just scanning a bigger or smaller grid.

Sudoku variants FAQ

What is a 4x4 Sudoku?

A 4x4 Sudoku uses a 4-by-4 grid split into four 2x2 boxes, filled with the numbers 1 to 4. It follows the same rule as classic Sudoku — no repeats in any row, column or box — just on a much smaller grid, which makes it a fast, gentle introduction for kids or beginners.

What is a 6x6 Sudoku?

A 6x6 Sudoku uses a 6-by-6 grid with the numbers 1 to 6, split into six 3x2 boxes. It's a step up from 4x4 and a step down from the classic 9x9, good for building speed and confidence.

What is a 12x12 Sudoku?

A 12x12 Sudoku uses the numbers 1 to 9 plus the letters A, B and C, split into twelve 4x3 boxes. It's a genuinely large puzzle that takes considerably longer to solve than a classic 9x9 grid.

What is a 16x16 Sudoku?

A 16x16 Sudoku, sometimes called giant Sudoku, uses the numbers 1 to 9 plus the letters A through G, split into sixteen 4x4 boxes. It's the largest common Sudoku variant and a serious challenge even for experienced solvers.

What is Killer Sudoku?

Killer Sudoku is played on a standard 9x9 grid with the usual row, column and box rules, plus one more layer: the grid is also divided into "cages" — groups of 2 to 5 cells marked by a dashed outline, each labeled with a small number that is the total its cells must add up to. No digit can repeat inside a cage, just like in a row, column or box. intosudoku's version keeps a handful of normal given digits on the board so you always have a foothold, with the rest solved from cage totals.

What is Compose Sudoku?

Compose lets you build your own puzzle instead of generating one. Pick any grid size from 4x4 to 16x16, type in your starting numbers, then press Start Sudoku to play it yourself or use Share to send it to a friend as a challenge link. Your starting numbers must follow the usual row, column and box rules, and the puzzle must have a valid solution.

Are all Sudoku variants solved the same way?

Yes. Every size follows the identical rule — each row, column and box contains every symbol exactly once — and every technique that works on a 9x9 grid works exactly the same way on 4x4, 6x6, 12x12 and 16x16.

Is Sudoku Variants free to play?

Yes. Every grid size and difficulty is free, generated fresh in your browser, with no sign-up and no limit on how many puzzles you play.

Prefer the classic grid? Play standard 9×9 Sudoku, or read our complete Sudoku guide.