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12×12 Sudoku: The Grid Where the Boxes Aren't Square

A 12×12 grid holds 144 cells and the digits 1–12, and every row, column and box takes each digit once. The interesting part is the box shape. Twelve has no whole-number square root, so the boxes cannot be square — they are 3 rows tall and 4 columns wide. That one detail is what separates this board from every square-box Sudoku you have played, and it is worth understanding before you start, because it changes which deductions come easily.

What the 3×4 box does to the grid

Because each box is 4 wide, the grid is 3 boxes across. Because each box is 3 tall, the grid is 4 boxes down. Twelve boxes in a 3-by-4 arrangement, and rows and columns no longer behave the same way:

• A row passes through 3 boxes, taking 4 cells from each.
• A column passes through 4 boxes, taking 3 cells from each.

On a 9×9 board those two sentences are identical. Here they are not, and every technique that involves a box interacting with a line inherits the difference.

The asymmetry you can actually exploit

Take a single box and ask where digit 7 can go inside it. The box has only three rows, so if 7 already appears in two of the rows crossing that box, it is pinned to the third — two eliminations and you have it. The box has four columns, so pinning 7 to a single column needs three eliminations.

Row-based cross-hatching therefore bites roughly a third sooner than column-based cross-hatching. When you are hunting for the next move on this board and have no particular reason to prefer one direction, scan rows first. It is a small edge, but on a grid this size a small edge compounds.

Two-digit numbers change how the board reads

A quarter of the symbols on this board — 10, 11 and 12 — take two characters instead of one. They render narrower than the single digits to fit the cell, and in a dense field of pencil marks the pair 11 / 12 is the one people most often misread at speed.

The practical habit worth building: when you write 11 or 12 into a cell, glance at the row once before moving on. Catching a slip in the moment costs a second. On a 144-cell grid, catching it forty cells later can cost the whole puzzle, because by then the error has propagated through every deduction you made in between.

Difficulty on this board

All four levels use the same generator and differ only in how many of the 144 cells start filled:

• Easy — 55 givens. Scanning and singles carry you most of the way. The right place to learn the 3×4 rhythm.
• Medium — 45 givens. Pencil marks stop being optional.
• Hard — 38 givens. Expect to need pointing pairs and box–line reduction.
• Expert — 32 givens, leaving 112 cells empty — more blanks than an entire 9×9 grid has cells.

A note on how this compares to 9×9: a 12×12 is more work but not proportionally harder to reason about. The extra constraints from the larger boxes give you more to eliminate with, so an Easy 12×12 is closer in difficulty to a Medium 9×9 than the raw cell count suggests. The real jump is in duration, not depth.

A solving order that works here

1. Open with the fullest boxes. With 12 digits per box, a box holding 6 or more givens is usually where the first placements are.
2. Scan rows before columns when cross-hatching, for the reason above.
3. Fill notes across a whole band at a time — the three boxes sitting side by side in one horizontal strip. Completing a band gives you a closed region to reason about instead of scattered cells.
4. Run single-digit sweeps once notes are in. Pick a digit, find every cell it can still occupy across all 144, and place what resolves.
5. Stop and re-check when a deduction surprises you. On a grid this long, a surprising move is more often an earlier mistake than a clever pattern.

Where to go next

• 6×6 Sudoku — rectangular 2×3 boxes; the same asymmetry, much faster.
• 16×16 Sudoku — back to square boxes at 4×4, with 256 cells.
• Classic 9×9 Sudoku — the standard board, four difficulty levels.
• Jigsaw Sudoku — regions that are not rectangles at all.
• Samurai Sudoku — five overlapping 9×9 grids if it is length you are after.

🖨️ Printable 12×12 Sudoku — Free PDF Downloads

Prefer solving on paper? Download our free printable 12×12 sudoku PDFs with solutions — larger grids with digits 1–12 in four difficulty levels:

• 12×12 Sudoku Easy PDF — More givens for a gentle introduction to the larger grid.
• 12×12 Sudoku Medium PDF — Fewer clues for solid cross-referencing practice.
• 12×12 Sudoku Hard PDF — Sparse givens requiring advanced techniques.
• 12×12 Sudoku Expert PDF — The toughest 12×12 puzzles for experts.

All downloads on our printable 12×12 sudoku page or the full printable sudoku collection.