Hard Sudoku Online

Hard sudoku puzzles are designed for solvers who have mastered the basics and are ready to push further. These grids start with significantly fewer given numbers, meaning basic scanning and elimination won't be enough to get you through. You'll need to apply intermediate and advanced techniques — pointing pairs, naked pairs, hidden pairs, and sometimes X-wing or swordfish patterns to make progress. Hard puzzles typically take 20 to 40 minutes even for experienced players, and the satisfaction of cracking one is well worth the effort. Every puzzle on Sudoku247 is logically solvable without guessing — if you're stuck, a technique exists to get you unstuck. Check our strategy guides for step-by-step walkthroughs of the techniques hard puzzles require. If hard is still not enough of a challenge, expert difficulty will push you to your absolute limit.