About 6×6 Hard Sudoku

A 6×6 Sudoku uses numbers 1–6 and six 2×3 boxes. Great for players who have mastered the 4×4.

At Hard difficulty, 30% of the 36 cells are pre-filled, leaving 25 cells for you to solve. Requires careful technique and pencil marks.

Tip: Use the Notes feature to pencil in candidates for each empty cell before committing.

Other difficulty levels for 6×6

How many hard 6×6 Sudoku puzzles are available?

Unlimited. Every time you click "New Game" a brand-new algorithmically generated puzzle is created. You will never run out of puzzles.

Are these puzzles printable?

Yes! Visit our printable Sudoku page to generate 4 puzzles per page as a PDF. Free, no login needed.

What solving techniques does Hard difficulty require?

Naked/hidden pairs, pointing pairs, and advanced elimination.

Free, instant, no login — works on mobile, tablet and desktop.