Sudoku Solver
Type in the clues from any 9×9 Sudoku — from a newspaper, a book, a screenshot — and this page solves it. It also tells you something most solvers do not: whether the puzzle you typed is well-formed, or whether it has no answer at all, or more than one.
What the three answers mean
- One solution. A proper Sudoku. The answer shown is the only one that fits.
- More than one solution. The clues do not pin the grid down. Usually a digit was mistyped or one was missed while copying; occasionally the source puzzle was genuinely broken.
- No solution. The clues contradict each other somewhere further along. This is different from two of the same digit in one row, which gets flagged before the solver even runs.
How it solves
It works the way a careful person does, only faster: it repeatedly picks the square with the fewest digits still legally possible, tries one, and continues — backing up the moment a square is left with no legal digit at all. Constraining the choice to the most restricted square first is what keeps the search small; a typical grid is solved in thousandths of a second.
Everything runs on your own device. Nothing you type is uploaded, and the page works offline once it has loaded.
A solver is a tool, not a shortcut
If you are stuck on a puzzle you want to finish yourself, a solved grid is the least useful thing to look at. Better to find the technique you are missing: the solving techniques guide covers them in the order they become necessary, and the per-level guides show which ones each difficulty actually demands.
Where the solver earns its place is checking a puzzle rather than beating it — confirming a grid you copied is valid, settling an argument about whether a puzzle has two answers, or verifying a Sudoku you have constructed yourself.
Or just play
Every puzzle generated on this site is checked for a unique solution before you ever see it, so it never needs the solver's verdict: easy, medium, hard and expert.