A samurai sudoku is five 9 by 9 sudokus arranged like the five on a die: one in each corner and one in the middle, which shares a 3 by 3 corner box with each of the others. Every samurai sudoku here comes from our generator, and the samurai sudoku solver proves the whole thing has one answer.
Rules
Each of the five grids follows the normal sudoku rules: every row, column and 3 by 3 box of that grid holds 1 to 9 once. The four shared boxes belong to two grids at the same time, so a digit placed there counts in both. Rows and columns stop at the edge of their own grid: a row of the top-left grid does not continue into the top-right one.
Levels
The puzzle has 369 squares. Easy keeps at least 200 given digits and singles finish it. Medium keeps at least 150 and needs nothing beyond Medium steps. Hard keeps at least 125 and needs a Medium to Expert step somewhere, such as a pointing pair, a triple or an X-wing. Levels come from the step-by-step rating of the whole puzzle.
How to approach a samurai
- Start where the clues are densest; often one outer grid is nearly solvable on its own.
- Work the shared corner boxes from both sides. A digit that one grid forces into the shared box is a gift to the center grid.
- Do not try to finish the grids one by one. Move between them whenever a shared box changes.
- On a phone, scroll the board sideways, or turn the phone, to see all five grids. The selected square stays highlighted while you scroll.
Play features
Pencil marks, undo and redo, Check, Show mistakes and the explained Hint work across all five grids, and squares are named by row and column on the big 21 by 21 board. A full samurai takes a while, so your progress, time and marks are saved in this browser and come back when you return. For a smaller challenge try sudoku online or killer sudoku online; for the methods, see how to solve sudoku.
Solver tested . Found a problem? Tell us.
Questions
How many squares does a samurai sudoku have?
369: five grids of 81 squares, minus the four shared boxes of 9 squares that would otherwise be counted twice.
Do rows run across two grids?
No. Each row and column belongs to one 9 by 9 grid. Only the four corner boxes of the center grid are shared.
Is my samurai saved if I close the page?
Yes. Your digits, pencil marks and time are stored in this browser and restored when you come back to this page.
Does a samurai sudoku have one solution?
Every grid here does: the solver checks the whole puzzle and keeps it only when exactly one answer exists.