Killer Sudoku

Killer Sudoku combines Sudoku with arithmetic. The grid follows the usual rules: every row, column and 3×3 box contains 1 to 9 once. In addition it is divided into dotted cages, each showing the sum of its digits, and a digit cannot repeat inside a cage. Few or no digits are given, so you must combine sums and Sudoku logic. Choose easy, medium or hard cage sizes; every puzzle has exactly one solution. Play Killer Sudoku free online in your browser — no download or sign-up needed.

Time 0:00Mistakes 0Best —

Fill the grid so every row, column and 3×3 box holds 1 to 9 once. The dotted cages show the sum of their digits, and a digit cannot repeat inside a cage. Select a square, then press a digit; use Notes for candidates. Keyboard: arrows move, 1–9 enter, Backspace erases, M toggles notes.

Game Information

Category
Puzzle Games
Players
Single player
Difficulty
Easy, Medium and Hard cage sizes
Game type
Numbers, Logic, Sums
Works on
Desktop and mobile browsers
Controls
  • Mouse or touch: select a square, then tap a digit on the pad
  • Keyboard: arrow keys move, 1 to 9 enter a digit, Backspace erases
  • Keyboard: M toggles notes, U undo, H hint, N new puzzle
Features
  • Three levels of cage size
  • Every puzzle has exactly one solution
  • Cage sums shown in each cage
  • Notes, undo and hints
  • Highlights repeated digits and wrong cage sums
  • Best time saved for each level

How to Play Killer Sudoku

Objective

Fill the grid with digits 1 to 9 so that every unit is complete and every cage adds up to its sum.

Starting a game

Pick a level. Dotted cages show a small number in their corner: that is the sum of the cage. A few squares may be given.

Rules

  • Each row, column and 3×3 box contains the digits 1 to 9 once.
  • The digits in a cage add up to the number in its corner.
  • A digit may not repeat inside a cage.
  • Given digits cannot be changed.

Controls

  • Mouse or touch: select a square, then tap a digit on the pad
  • Keyboard: arrow keys move, 1 to 9 enter a digit, Backspace erases
  • Keyboard: M toggles notes, U undo, H hint, N new puzzle

Winning and losing

You win when every square is correct. Mistakes are counted but do not end the game.

Tips and Strategies

  • Start with single-square cages: the sum is the digit.
  • Cages of two squares with sums like 3 or 17 have only one possible pair of digits.
  • A cage cannot repeat digits, which limits the combinations for its sum.
  • Add up the sums of cages that fill a row, column or box: they must total 45.
  • Use notes for the possible digits in each cage.

Frequently Asked Questions

Why are no digits given?

The cage sums replace most of the givens. When a puzzle needs help to have just one solution a few digits are given.

Can a digit repeat in a cage?

No. Every cage uses different digits.

What do the dotted lines mean?

They mark the outline of a cage. Its sum is printed in the top-left corner.

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