How do you play Killer Sudoku?

Every row, column and 3 by 3 box holds 1 to 9 once. Each dashed cage adds up to its corner sum without repeating a digit. A two-square cage with sum 3 uses 1 and 2; the rows, columns and boxes decide their positions. The cage sums total 405, because each of the nine rows totals 45. Tap a square and type 1 to 9, or use the digit pad. Notes switches to pencil marks; Delete, Backspace or 0 erases. A full grid counts as solved only when every rule holds.

Does every Killer Sudoku here have exactly one solution?

Each released puzzle is checked for exactly one solution. If a requested seed cannot finish within the fixed step limits, the page opens one of 12 verified seeds instead and shows the reason and actual seed. A fallback can repeat a puzzle, including on different daily dates. There are no given digits; the cage sums are the starting clues.

What does the small number in a cage mean?

It is the total of the cage's digits. Select a square to see its cage letter, size, sum and remaining digit sets in the side pane. A set does not mean every ordering is allowed: rows, columns and boxes still constrain the positions. The cage list also shows all sums as text.

Press Notes, or N on a keyboard, to add or remove pencil notes in an empty square. Press it again to enter digits. Entering a digit clears that square's notes. Notes never count as filled squares. They are saved with progress and can be undone.

What do Check, Reveal cell and Hint do?

Check outlines typed digits that differ from the solution until your next move. Reveal cell fills and locks the selected square. Hint explains a clash, a cage problem or a wrong digit first, then a forced move when possible; otherwise it names one answer. It never enters the answer for you. Checking typed digits, successfully revealing a cell, or receiving a hint marks the game assisted, and Undo keeps that mark. Automatic rule-conflict highlights are not assists.

Can I print a Killer Sudoku puzzle?

Print puzzle opens the browser print dialog with the cages, sums and seed. Tick the answer-key option for a second page, or use Print answer key for the solved grid alone. The grid is 162 mm square. Choose Save as PDF if your browser offers it. Copy takes the cage-letter grid, entered digits and all sums as text; notes are marked with an asterisk, without listing their digits. Dated puzzles include the UTC date in copied text and printed headings.

What is the seed, and can I play the same puzzle again?

A seed is a whole number from 1 to 999999. Type it in Seed and press Play seed to replay that puzzle; New puzzle chooses a random seed. The actual seed above the grid identifies the puzzle, including after a fallback. Seeds reproduce the same cage layout and solution.

Is my progress saved, and is there a timer?

Progress stays in this browser: digits, notes, assists, timer and up to 9 earlier played puzzles. Resume reopens earlier progress, while Play again opens a solved puzzle empty. Dated selection restores matching saved progress by actual seed. The date label lasts for the current visit; a reload resumes by seed. Undo covers up to 400 moves since opening a puzzle in this visit. Timer counts while the tab is visible and the puzzle is unsolved. Start over forgets this tool's saved progress. If storage is refused, play continues with a message.

How do I play the daily puzzle or browse earlier dates?

Press Today's puzzle to use today's UTC date. For the date archive, choose any date from 2000-01-01 through today in Puzzle date (UTC), then press Play date. Each date requests a fixed seed and opens a playable grid, so it works without an account. This is a generated date archive, not a collection of another publisher's past puzzles. A fallback can repeat a layout on different dates. The grid heading shows the installed date and actual seed; changing the date field alone does not change the board.

Can I play free on an iPad or in a UK browser?

Yes. This browser game has no account or payment step. Use the square selector and digit pad on an iPad, or a keyboard on a computer. Progress is local to that browser and does not sync between devices. The interface is in English, including when you access it from another country.

Are there easy, hard or expert levels, or a solver for my own puzzle?

The generated puzzles have no tested difficulty grade, so a cage count is not an easy, hard or expert level. Hints and Reveal cell apply to the puzzle currently on this page. There is no editor to enter and solve your own cage layout, and no Samurai or greater-than variant.

Is sum Sudoku the same game?

Sum Sudoku commonly refers to this cage-sum form of Sudoku: each cage adds to its total and cannot repeat a digit. The board here uses those rules together with the ordinary row, column and 3 by 3 box rules.

Killer Sudoku

Play a free Killer Sudoku in your browser. Fill each row, column and 3 by 3 box with 1 to 9 once; each dashed cage adds up to its sum without repeating a digit. Tap a square and use the digit pad or keyboard. Notes, undo, hints and a timer help you play. Choose Today's puzzle for the UTC daily selection, or choose an earlier Puzzle date and press Play date. Seeds replay puzzles, and progress stays in this browser. Cage counts describe the layout, not a tested difficulty.

puzzleno puzzle yet

Setting up the board

Your saved puzzle, or a new one, appears here in a moment.

cagessaved once you play

rules: Each row, column and 3 by 3 box holds the digits 1 to 9, each once. The digits in each dashed cage add up to the small sum in its corner, and a cage never repeats a digit.
sums: none yet
status: none yet
timer: off
keys: arrows move, 1 to 9 enter, N notes, Delete erases

Setting up the board.

Filled: none yet

Cages: none yet

Notes: none yet

Status: none yet

Seed

Puzzle date (UTC)

Today uses the UTC calendar date. Choose an earlier date to play its puzzle. Dates can repeat a puzzle after fallback; the actual seed stays visible. Saved progress resumes by seed, with the date label shown during this visit.

Print puzzle adds the answer key on a second page

Tap a square, or move to it with the arrow keys, then type a digit or press one on the pad under the grid. Notes (or N) switches the digits to notes and back; notes never count as filled squares. Delete, Backspace or 0 erases, and Ctrl+Z or Cmd+Z undoes. A square turns red the moment its digit repeats in a row, column, box or cage, or its cage can no longer reach its sum. Check compares your digits with the solution, Reveal cell fills the selected square from it, and Hint names a clash or a broken cage first, then a digit that is not part of the only solution, then the next square you can work out and why. Checking typed digits, successfully revealing a cell, or receiving a hint marks the game assisted, and undo does not remove the mark. The seed on the board makes the same puzzle again anywhere, and your progress stays in this browser.

Your recent puzzles

No earlier puzzles yet. Each puzzle you leave with a digit, a note or an assist used is kept here with its seed and your progress, up to 9, so you can go back to it.

How the rules are checked

Two-cell cage, sum 31 and 2, or 2 and 1
the only fill; 2 and 2 fails even in a sum 4 cage, since a cage never repeats a digit
Reveal one cellany empty cell
the answer is filled in and locked, and the puzzle is marked assisted; undo removes the digit, not the mark
Save, reload or print31 digits and 2 cells of notes
the same cages and sums; notes stay notes and never count as solved digits

Accuracy. Every row, column and 3 by 3 box holds 1 to 9 once, and each cage's digits add up to its sum without repeating; a clash or a cage total that cannot work is marked as soon as it is typed. Every puzzle is original, built on this page from its own solved grid by joining cages, and each join is kept only after a solver working within a set step limit proves the puzzle still has exactly one solution. The label on a puzzle counts its cages; it is not a tested difficulty, and daily puzzles use UTC dates with possible repeats when a build falls back.

Common questions

How do you play Killer Sudoku?: Every row, column and 3 by 3 box holds 1 to 9 once. Each dashed cage adds up to its corner sum without repeating a digit. A two-square cage with sum 3 uses 1 and 2; the rows, columns and boxes decide their positions. The cage sums total 405, because each of the nine rows totals 45. Tap a square and type 1 to 9, or use the digit pad. Notes switches to pencil marks; Delete, Backspace or 0 erases. A full grid counts as solved only when every rule holds.
Does every Killer Sudoku here have exactly one solution?: Each released puzzle is checked for exactly one solution. If a requested seed cannot finish within the fixed step limits, the page opens one of 12 verified seeds instead and shows the reason and actual seed. A fallback can repeat a puzzle, including on different daily dates. There are no given digits; the cage sums are the starting clues.
What does the small number in a cage mean?: It is the total of the cage's digits. Select a square to see its cage letter, size, sum and remaining digit sets in the side pane. A set does not mean every ordering is allowed: rows, columns and boxes still constrain the positions. The cage list also shows all sums as text.
How do notes work?: Press Notes, or N on a keyboard, to add or remove pencil notes in an empty square. Press it again to enter digits. Entering a digit clears that square's notes. Notes never count as filled squares. They are saved with progress and can be undone.
What do Check, Reveal cell and Hint do?: Check outlines typed digits that differ from the solution until your next move. Reveal cell fills and locks the selected square. Hint explains a clash, a cage problem or a wrong digit first, then a forced move when possible; otherwise it names one answer. It never enters the answer for you. Checking typed digits, successfully revealing a cell, or receiving a hint marks the game assisted, and Undo keeps that mark. Automatic rule-conflict highlights are not assists.
Can I print a Killer Sudoku puzzle?: Print puzzle opens the browser print dialog with the cages, sums and seed. Tick the answer-key option for a second page, or use Print answer key for the solved grid alone. The grid is 162 mm square. Choose Save as PDF if your browser offers it. Copy takes the cage-letter grid, entered digits and all sums as text; notes are marked with an asterisk, without listing their digits. Dated puzzles include the UTC date in copied text and printed headings.
What is the seed, and can I play the same puzzle again?: A seed is a whole number from 1 to 999999. Type it in Seed and press Play seed to replay that puzzle; New puzzle chooses a random seed. The actual seed above the grid identifies the puzzle, including after a fallback. Seeds reproduce the same cage layout and solution.
Is my progress saved, and is there a timer?: Progress stays in this browser: digits, notes, assists, timer and up to 9 earlier played puzzles. Resume reopens earlier progress, while Play again opens a solved puzzle empty. Dated selection restores matching saved progress by actual seed. The date label lasts for the current visit; a reload resumes by seed. Undo covers up to 400 moves since opening a puzzle in this visit. Timer counts while the tab is visible and the puzzle is unsolved. Start over forgets this tool's saved progress. If storage is refused, play continues with a message.
How do I play the daily puzzle or browse earlier dates?: Press Today's puzzle to use today's UTC date. For the date archive, choose any date from 2000-01-01 through today in Puzzle date (UTC), then press Play date. Each date requests a fixed seed and opens a playable grid, so it works without an account. This is a generated date archive, not a collection of another publisher's past puzzles. A fallback can repeat a layout on different dates. The grid heading shows the installed date and actual seed; changing the date field alone does not change the board.
Can I play free on an iPad or in a UK browser?: Yes. This browser game has no account or payment step. Use the square selector and digit pad on an iPad, or a keyboard on a computer. Progress is local to that browser and does not sync between devices. The interface is in English, including when you access it from another country.
Are there easy, hard or expert levels, or a solver for my own puzzle?: The generated puzzles have no tested difficulty grade, so a cage count is not an easy, hard or expert level. Hints and Reveal cell apply to the puzzle currently on this page. There is no editor to enter and solve your own cage layout, and no Samurai or greater-than variant.
Is sum Sudoku the same game?: Sum Sudoku commonly refers to this cage-sum form of Sudoku: each cage adds to its total and cannot repeat a digit. The board here uses those rules together with the ordinary row, column and 3 by 3 box rules.

Every row, column and 3 by 3 box holds 1 to 9 once, and each cage's digits add up to its sum without repeating; a clash or a cage total that cannot work is marked as soon as it is typed. Every puzzle is original, built on this page from its own solved grid by joining cages, and each join is kept only after a solver working within a set step limit proves the puzzle still has exactly one solution. The label on a puzzle counts its cages; it is not a tested difficulty, and daily puzzles use UTC dates with possible repeats when a build falls back.