Sudoku — play the free online number puzzle
Fill the 9×9 grid so every row, column, and 3×3 box holds the digits 1–9. Free, no download, with Easy to Expert boards, pencil marks, undo, and hints.
- Easy · Medium · Hard · Expert
- Every puzzle has one solution
- Progress saved on your device
Ready to play?
Pick a difficulty and solve the 9×9 grid.
What is Sudoku
A pure test of logic on a 9×9 grid
Sudoku is a single-player logic puzzle. Fill the grid so every row, every column, and every 3×3 box holds the digits 1 to 9 exactly once. No arithmetic, no luck — just deduction. The rules take seconds to learn; reading the board well enough to finish an Expert puzzle is what keeps players coming back.
- Four difficulty levels
- Easy, Medium, Hard, and Expert — set by the number of givens and the techniques a puzzle needs, not by changing the rules.
- Always one solution
- Every puzzle is generated and verified to have exactly one solution, so it is always solvable by logic — never by guessing.
- Notes, undo, and hints
- Pencil-mark mode, one-cell hints, and step-by-step undo are built in. Placing a digit prunes candidates for you automatically.
- Your game is saved
- The puzzle in progress, best times, and streaks are stored on your device. Close the tab and pick up exactly where you left off.
How to play
How to play Sudoku
Sudoku is a logic puzzle with one rule: every row, column, and 3×3 box holds the digits 1 to 9 exactly once. Placing the forced digits first is what turns a stuck grid into a finished one.
- 1
Read the grid
A Sudoku is a 9×9 grid split into nine 3×3 boxes. Some cells already hold digits — the givens. The rest are yours to fill.
- 2
One of each, everywhere
Every row, every column, and every 3×3 box must contain the digits 1 to 9 exactly once. No digit may repeat in any row, column, or box.
- 3
Place what must be true
Look for a cell where only one digit can legally go, or a digit that fits only one cell in a row, column, or box. Enter it and move on.
- 4
Finish with no repeats
Keep going until all 81 cells are filled. There is exactly one valid solution, so a correct grid is the finished puzzle.
Tips to solve faster
- Scan rows, columns, and boxes for a digit that already appears three or four times — it is often forced into one remaining cell.
- Turn on notes and pencil in every candidate for a cell. A cell with a single candidate is a "naked single" you can place immediately.
- A digit that can only go in one cell of a box, row, or line is a "hidden single", even if that cell has several candidates.
- When two cells in a unit share the same two candidates, those digits are locked to that pair — erase them from the rest of the unit.
- If a box’s candidates for a digit all sit in one row or column, that digit cannot appear elsewhere in that row or column (pointing pair).
- Fill the boxes and rows with the most givens first; each digit you place removes candidates elsewhere and unlocks the next step.
- Never guess. Every solvable position has a logical next move — if you cannot find one, look again at the digits you have placed most.
FAQ
Sudoku, answered
Authoritative answers about Sudoku — the free 9×9 logic puzzle you can play online in your browser.
What is Sudoku?
Sudoku is a single-player logic puzzle played on a 9×9 grid divided into nine 3×3 boxes. Some cells start filled with digits called givens. Your job is to fill every remaining cell so that each row, each column, and each 3×3 box contains the digits 1 through 9 exactly once. No arithmetic is involved — it is pure deduction. The modern puzzle was popularised in Japan in the 1980s under the name Sudoku ("single number") and became a worldwide fixture after 2004.
Is Sudoku free to play here?
Yes. sudokupuzzles.games is completely free and runs entirely in your browser. There is nothing to buy, download, or install, no account, and no ads interrupting a puzzle. Open the page and a board is ready.
How do I play Sudoku?
Select an empty cell and enter the digit that must go there. A digit is correct when it does not already appear in that cell’s row, its column, or its 3×3 box. Work through the grid placing forced digits — cells where only one digit fits, or digits that fit only one cell in a unit — until all 81 cells are filled. There is exactly one valid completion.
Does every Sudoku have only one solution?
A proper Sudoku has exactly one solution, and every puzzle on this site is checked for that before it is served. That is what makes the puzzle solvable by logic alone: you never have to guess, because at any point there is a digit that must be true.
What does the mistake limit mean?
Entering a digit that does not match the unique solution counts as a mistake; the cell turns red and the counter goes up. Three mistakes ends that game. It is a light guardrail rather than a harsh penalty — you can start a new puzzle instantly, and taking your time to think never costs anything.
What are notes or pencil marks?
Notes mode lets you write small candidate digits into a cell instead of a final answer — the same thing players do with a pencil on paper. When you later place a confirmed digit, that candidate is automatically erased from every cell in the same row, column, and box so your notes stay accurate.
How do hints work?
A hint fills the selected empty cell with its correct digit and locks it, the same as a given. If no cell is selected, the hint reveals the next unsolved cell. Hints are tracked on screen but carry no penalty beyond that tally.
How is difficulty decided?
Difficulty is set by how many digits the puzzle starts with and which solving techniques are needed to finish it. Easy boards (around 40 givens) fall to simple scanning. Medium needs pencil marks and hidden singles. Hard brings in naked and hidden pairs. Expert (around 24 givens) rewards pointing pairs, box/line reduction, and patience. The rules and the 9×9 grid never change between levels.
How do you get better at Sudoku?
Learn to spot naked singles (a cell with one candidate) and hidden singles (a digit with one home in a unit) quickly, then add naked pairs and pointing pairs. Use notes on anything above Easy. Practising the same difficulty repeatedly trains pattern recognition faster than jumping straight to Expert. Our tips page walks through each technique.
Does sudokupuzzles.games save my progress?
Yes. Your current in-progress puzzle is saved in your browser, so closing the tab and returning later picks up where you left off. Best times, games won, and streaks are also stored per difficulty. Nothing is sent to a server, and there is no login, so a different device or browser starts fresh.
Can I play Sudoku on mobile?
Yes. The layout is built for phones and tablets: the board and number pad fit a portrait screen without scrolling, and a tool row covers notes, erase, undo, and hints. Tap a cell, then tap a digit.