Easy Killer Sudoku — Free Online Puzzle

How to play

Fill the grid with digits 1 to 9. Each row, each column and each three-by-three box must contain every digit exactly once. The dashed outlines mark cages. The small number at the top-left of a cage is its total: all digits inside must add to that number, and a digit may never repeat anywhere in the same cage, even across different rows or boxes.

Select a square, then tap the number pad or type a digit. Switch Notes on to pencil in possible digits instead of filling a square. Tap a pencilled digit again to remove it. A real entry clears that square’s notes and removes the digit from notes in its row, column, box and cage. Erase clears the selected square; Undo restores the previous entry and its notes.

Red squares flag repeated digits in a row, column, box or cage. A completed cage with the wrong total is also highlighted. Check compares your current entries with the answer and tells you how many need another look. Show solution reveals every digit and stops the timer; it does not earn a daily solve. Reset clears the same grid so you can start again.

A short history

Killer sudoku combines the familiar nine-digit grid with arithmetic clues. It developed in Japan as a sum number place variant during the 1990s, and The Times helped bring it to English-speaking newspaper readers in 2005. The cage totals create a different starting point from ordinary sudoku: in the classic form, you begin without any filled digits and use the sums together with the row, column and box rules. Read the puzzle history.

Play one shared medium puzzle each UTC day, or choose easy, medium or hard practice. Easy starts with six given digits and mostly small cages. Medium and hard begin with zero given digits; hard allows more merges into larger cages. These labels describe cage sizes and starting help, rather than a measured solving technique. Every grid has exactly one solution. New puzzle changes your practice seed and share link in this browser; the published starting puzzle stays fixed.

Solving tips

Small totals can pin down a combination. A total of 3 in two cells must be 1 and 2; a total of 4 in two cells must be 1 and 3. A total of 6 in three cells must be 1, 2 and 3. These combinations identify the digits, but you still need the intersecting row, column and box to decide their order. Never use a repeated digit to reach a total.

Every complete row, column and box adds to 45. Compare that total with cages entirely inside the region. If only one square is left outside those cages, subtract their totals from 45 to find its digit. Take care when a cage crosses the boundary: its entire sum does not belong to the region, so you cannot subtract it as though it did.

Use notes to record candidates and revisit neighboring cages after every confirmed digit. Bigger cages permit more combinations, so a smaller cage or an almost complete row is often a useful place to start. The timer starts on your first entry and pauses when you finish. There is no countdown or time limit.

Progress, time and streak stay on this device. A daily streak counts consecutive UTC days solved without revealing the answer; solving a date twice adds nothing. A dated daily share link keeps the same puzzle available later. Share includes your time and puzzle address, without digits, cages or an answer grid.