Does every sudoku have only one solution?
Updated 15 September 2026
A proper sudoku has exactly one solution. Every board from our generator is verified to be uniquely solvable, so it is never ambiguous or unsolvable, and the printed solution is the only answer.
A sudoku with more than one solution is considered broken, because it cannot be solved by logic alone. Our engine checks every board with a solver as it removes numbers, and keeps a number removed only while a single solution still holds.
The same guarantee carries into a published book: every puzzle in a Publisher Studio interior is uniquely solvable, and the solutions section matches each board.