Sudoku free online
Sudoku is the world's most-played logic puzzle: fill the 9×9 grid so every row, every column, and every 3×3 box contains the digits 1 through 9 exactly once. No math, no vocabulary — pure deduction.
Every puzzle here is generated with a guaranteed unique solution and graded by the techniques actually required to solve it, not just by how many clues it shows. Play free in your browser on any device; your in-progress puzzle saves automatically.
Three free puzzles a day per difficulty. Stuck on a hard one? A quarter buys a hint that shows the next logically forced cell — a teaching hint, not a spoiler. And Today's Odds serves one identical daily puzzle worldwide with a time leaderboard.
Difficulty modes
Easy
Easy sudoku puzzles use straightforward singles: in every position there is at least one cell whose value can be placed with simple scanning. Perfect for learning the rules or a low-effort coffee-break solve. Typical solve time: 3–8 minutes.
Medium
Medium puzzles require systematic candidate elimination — naked pairs and pointing pairs start to appear. This is the sweet spot for a daily desk solve: engaging without being a project. Typical solve time: 8–15 minutes.
Hard
Hard puzzles demand real technique: hidden pairs, box-line reduction, and X-wing patterns. Pencil marks are no longer optional. A quarter buys a hint that reveals the next logically deducible cell when you're stuck. Typical solve time: 15–30 minutes.
Expert
Expert boards open with very few givens and require chained inference — swordfish, XY-wings, and long elimination chains. These are genuinely difficult puzzles intended for experienced solvers. Typical solve time: 30+ minutes.
Frequently asked questions
Are these sudoku puzzles free?
Yes — three free puzzles per difficulty per day, plus the free daily challenge. Quarters only buy extras: hints, auto-checking, and continues after three mistakes.
Does every puzzle have exactly one solution?
Yes. Every board is machine-verified to have a unique solution before it's served. If logic seems to run out, there is always a deduction available — that's what the hint button finds.
What's the difference between easy and expert sudoku?
The techniques required. Easy puzzles solve with simple scanning; expert puzzles require advanced elimination patterns like X-wings and chained inferences. Clue count alone doesn't determine difficulty.
Is sudoku good for your brain?
Sudoku exercises working memory, pattern recognition, and systematic reasoning. Research on puzzles suggests regular mental challenge supports cognitive engagement, though it isn't a medical treatment for anything — it's just genuinely good practice in careful thinking.
What is the daily sudoku?
Today's Odds is one identical puzzle served to every player in the world each day, free to attempt once. Finish it to log your time on the leaderboard and copy a spoiler-free result grid to share.
How do hints work?
A hint costs 1 quarter and reveals the next cell that is logically forced given the current board, along with which row, column, or box forces it — so you learn the technique instead of just getting an answer.
More games: Minesweeper · Klondike Solitaire · Snake · Stacks