Sudoku Online

Your Rank — Sudoku

Sudoku Leaderboard

Sudoku Online - Pure Logic, No Guessing

How to play

Tap a cell, then tap a number on the pad (or type 1–9). Each row, column and 3×3 box must end up with the digits 1 to 9 exactly once. A wrong digit turns red and costs one of your three mistakes; the third one ends the puzzle.

Strategy that works

Start with the most crowded rows and boxes and look for a cell where only one digit fits. Then scan each digit across the board: if a box has only one place left for a 7, it goes there. On harder grids, pencil in candidates and look for pairs that lock other cells.

Four difficulty levels

Easy grids fall to simple singles. Medium needs hidden singles, Hard brings locked candidates and pairs, and Expert asks for triples, hidden pairs and X-Wings. Every board is reshuffled from a technique-rated puzzle, so it always has exactly one solution and never needs guessing.

Notes, hints and scoring

Notes mode lets you write small candidates in a cell, and placing a digit clears it from the notes of its row, column and box. You get three hints per puzzle. Correct digits score points, and a solve adds a bonus for speed and for zero mistakes. Your best score per level is saved in your browser.

How the score is calculated

Every correct digit is worth 10 points times the level multiplier: ×1 on Easy, ×2 on Medium, ×3 on Hard and ×4 on Expert. Each cell pays only once, so erasing a digit and typing it again earns nothing, and a digit placed by a hint is worth zero. Finishing the grid adds a solve bonus of 300 points, one point for every second left under par and another 200 for a game without mistakes, all multiplied by the level. Par is 4 minutes on Easy, 7 on Medium, 11 on Hard and 15 on Expert.

Stars and par time

A solved puzzle earns three stars if you beat par with no mistakes, two stars if you stay within 1.6 times par, and one star otherwise. The clock only runs while you play: the pause button stops it, and switching to another tab pauses the game for you. Since faster solves score more, fill the obvious singles quickly and save careful note work for the cells that really need it.

Keyboard, hints and undo

Arrow keys move the selection, 1–9 enter a digit, N switches notes on and off, Z or Ctrl+Z undoes and H takes a hint. A hint fills the selected cell with its correct digit; if no empty cell is selected, it picks the most constrained open cell on the board, the one with the fewest candidates left. Undo steps back through digits and notes as far as you like, but a mistake stays on the counter even after you undo the wrong digit.

Saved games and the leaderboard

Each level keeps its own unfinished puzzle in your browser, so you can close the page and pick it up later with Continue. Your best score and the number of grids you have solved are stored per level on this device. If you are signed in, finished games – won or lost – are also sent to the Sudoku leaderboard; guests play entirely offline. A puzzle that ends on the third mistake keeps the points earned so far, and they can still set a new best.

More logic games

Sudoku trains the same careful scanning as other deduction puzzles. In Minesweeper numbers tell you how many mines touch a square, the memory game tests how many card positions you can keep in mind, and 2048 is a number puzzle about merging tiles rather than placing them.

Sudoku – FAQ

Does every puzzle have exactly one solution?

Yes. Medium, Hard and Expert grids are reshuffled from technique-rated puzzles by swapping rows, columns, bands and digits, which keeps the single solution. Easy grids start from a rated board and gain extra clues until simple singles solve them.

What happens after three mistakes?

The puzzle ends. The points you earned still count, and if they beat your best for that level they become the new best.

Do hints lower my score?

A hint takes no points away, but the digit it places is worth nothing, and each puzzle has only three hints.

Your Rank — Sudoku

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