Hard Sudoku Free Online | Play Hard Sudoku Puzzles, Unlimited

See rankings →Daily Sudoku →Printable Sudoku →Large Print Sudoku →4x4 Sudoku →6x6 Sudoku →Sudoku strategies →

How to solve Hard puzzles

Turn on Notes and tap numbers to pencil in candidates.

If two cells in the same row, column or box can only be the same two numbers (say 3 and 7), no other cell in that unit can be 3 or 7. Remove them from the others.

When you place a correct number, it is removed from the notes in the same row, column and box automatically.

Techniques for this level

Hidden Single: A number that fits in only one cell of a unit
Naked Pair: Two cells, same two candidates: clear those numbers from the rest of the unit
Pointing Pair: A box's candidates in one line clear the rest of the line

All Sudoku strategies →

About this level

Is Hard the hardest level on puzuru?

No. Above Hard come Expert, Master, Extreme and Evil. Hard is where notes start to pay off; Expert is where the basics stop being enough.

Can I print hard Sudoku puzzles?

Yes. The printable page makes A4 or Letter sheets for every level except Evil, with answers on a separate page.

Difficulty levels

Level	Given numbers	What it takes
Easy	40	Fill cells that have only one possible number
Medium	32–33	Same technique, fewer clues, more searching
Hard	26–28	Use notes; pairs and pointing at most
Expert	26 or fewer	Basics always stall; pairs or pointing required
Master	28 or fewer	Pairs stall; X-Wing or XY-Wing required
Extreme	26 or fewer	Even X-Wing stalls
Evil	26 or fewer	The Extreme puzzles that need the deepest reasoning. The hardest level

How to play

1. Pick a level

Choose one of seven levels from Easy to Evil. You get a new puzzle each time.

2. Fill in numbers

Tap a cell, then a number. Each row, column and 3x3 box must contain 1 to 9 exactly once.

3. Complete the grid

Use Notes to pencil in candidates. Wrong numbers turn red.

Full rules and how to play →

FAQ

Is it free?

Yes. All seven levels are free. No sign-up.

Does every puzzle have one solution?

Yes. Each puzzle is checked by the program to have exactly one solution.

Will I lose my progress if I leave?

No. Open the same level on the same device and browser to continue. One game is saved per level.

What is the "???" button?

It's a secret stage with 3 special puzzles you won't find anywhere else (3 levels). Share, or enter the password, to open it. The password is in the share text and changes every Monday.

What are the daily stamps?

You get one stamp on each day you play. The days don't need to be in a row. Every 7th stamp is gold: it unlocks a board theme and gives you a 🎟️ mistake pass. Your stamps are saved only in this browser (no sign-up).

What is the 🎟️ mistake pass?

It lets you undo a mistake. You get one every day (use it that day) and one with each gold stamp (you can keep these). Tap the button that appears when you make a mistake. Your time still counts for the ranking.

Are there ads?

We never interrupt you with ads while you're solving a puzzle.

Can I play on my phone?

Yes. No install needed. On a computer you can also use number keys, arrow keys and N to toggle notes.

More games

SolitaireClassic Klondike. Every deal is checked to be winnable.Mahjong SolitaireClear the board by matching pairs of tiles.Spider SolitaireBuild runs from King to Ace. Every deal is verified winnable.CheckersThe classic jump-and-capture board game. Five computer levels, or play a friend on the same device.FreeCellFour free cells, pure strategy. Classic game numbers, every deal verified winnable.HeartsThe classic trick-taking card game. Play against 3 computer opponents.Reversi (Othello)The classic disc-flipping board game. Five computer levels, or play a friend on the same device.GomokuGet five in a row before your opponent. A 15×15 board, five computer levels, or play a friend on the same device.MancalaSow stones and fill your store. The popular six-pit, four-stone rules, five computer levels, or play a friend on the same device.Four in a RowDrop discs and line up four before your opponent. A 7×6 board, five computer levels, or play a friend on the same device.Five DiceRoll five dice up to three times, make combinations and fill 15 boxes. Go for a high score solo, or play the computer or a friend.Tic-Tac-ToeGet three in a row before your opponent on a 3×3 grid. Five computer levels, or play a friend on the same device.Mahjong ConnectJoin matching mahjong tiles with a line of up to two turns. Three board sizes up to the classic 8×17. Every deal can be cleared.DaifugoThe Japanese climbing card game: be first to empty your hand. 8-stop, revolution and the card exchange, 5 rounds against 3 computer players.Gin RummyDraw, discard and meld your hand into sets and runs. Knock with 10 or less deadwood or go gin. One-on-one against the computer, first to 100 wins.Word SearchFind the hidden words across, down and diagonally. Ten themes, three sizes from 8×8 to 15×15, a new puzzle every time, and printable.SevensBuild each suit out from the 7s and be first to empty your hand. Up to 3 passes per round, 5 rounds against 3 computer players.Tower of HanoiMove the whole stack of disks to the right rod, one disk at a time, never placing a larger disk on a smaller one. 3 to 8 disks, aim for the minimum moves.Sliding PuzzleSlide the tiles into the empty space to put the numbers in order. 3×3, 4×4 (the classic 15 puzzle) and 5×5. A new, solvable puzzle every time.Yukon SolitaireA Klondike-style solitaire with no stock pile. Any face-up card moves together with the cards on top of it. Every deal can be won.Scorpion SolitaireBuild down in suit and complete four columns from King to Ace. Any face-up card moves together with the cards on top of it.SpadesThe classic partnership card game where spades are trump. Team up with a computer partner.BackgammonRoll the dice and race your 15 checkers home. Five computer levels, or play a friend on the same device.2048Slide and merge matching tiles to reach 2048. Boards from 3×3 to 6×6, with undo.MazeDrag from start to exit. 8×13 to 30×53, a new maze every time, and printable.NonogramFill the grid from row and column number clues. 5×5 to 20×20, every puzzle solvable by logic alone.Matching GameTurn over two cards and match the pictures. Animals, food and vehicles, 8 to 24 pairs.ConcentrationThe classic memory card game: turn over two cards and match pairs. Four levels, 8 to 24 pairs.TriPeaks SolitaireChain cards one higher or lower to clear three peaks of cards.Golf SolitairePlay cards one higher or lower to clear all seven columns. Every deal is winnable.Pyramid SolitairePair cards that add up to 13 to clear the pyramid. Every deal is winnable.MinesweeperOpen every safe cell using the numbers. Every board can be solved by logic alone.Killer SudokuNo given numbers. Solve it from the cage sums alone.