Sudoku Solver
Stuck on a Sudoku? Type the puzzle into the grid below and tap Solve — this free solver fills in the answer instantly and tells you whether the board has a single valid solution. Enter your given numbers, hit Solve, and the computed digits appear in green. No download, no sign-up.
How to use the Sudoku solver
- Tap a cell, then type its given digit (1–9) — on a phone use the on-screen keypad.
- Enter every number from your puzzle and leave the unknown cells blank.
- Tap Solve — the answer fills in, with the solver’s computed digits shown in green.
- If your clues conflict, have no solution, or allow more than one, the solver tells you so you can fix them.
- Tap Clear to wipe the grid and start another puzzle.
How the solver works
The solver reads the numbers you enter and works out the answer the same way a person would — by logical elimination — then backtracks through the remaining possibilities until the grid is complete. It also counts the solutions, so it can tell you whether your clues lead to one unique answer or several.
Because it follows the real rules of Sudoku (each digit once per row, column and 3×3 box), the result is always a valid completion of the numbers you typed. If no completion exists, it says so rather than guessing.
When to use a Sudoku solver
- You are truly stuck. Get the next digit or the full answer when a newspaper or app puzzle has you beaten.
- Check your work. Enter your finished grid to confirm it is correct, or enter your progress to see if you have gone wrong.
- Test a puzzle you made. The solver flags whether a board has exactly one solution — essential if you are designing your own.
- Settle a tricky spot. See the solution to a single hard region, then go back and finish the rest yourself.
Is using a solver cheating?
A solver is a tool, not a shortcut around the fun — how you use it is up to you. Many players solve as far as they can, then use it only to confirm an answer or unstick one cell, which is a great way to learn new patterns without abandoning a puzzle. If you would rather build the skill from scratch, try our tips and strategy guide and beginner’s guide, then play a fresh board.
Sudoku solver: FAQ
How do I use the Sudoku solver?
Tap a cell and type its given digit, entering all the numbers from your puzzle and leaving the rest blank. Then tap Solve — the answer appears, with the solver’s computed digits shown in green. Tap Clear to start over.
Does it solve any Sudoku?
It solves any standard 9×9 Sudoku that has a valid solution. If the numbers you enter conflict (a repeated digit in a row, column or box) or cannot be completed, the solver tells you instead of returning a wrong answer.
Will it tell me if my Sudoku is unsolvable or has multiple solutions?
Yes. The solver checks how many solutions your clues allow: it warns you if the clues conflict, if there is no solution at all, or if the board has more than one solution (which usually means a clue is missing).
Is the Sudoku solver free?
Yes — it runs free in your browser on phone, tablet and desktop, with no download and no sign-up. Nothing you type is sent anywhere; the solving happens on your own device.
Can a solver help me get better at Sudoku?
Used sparingly, yes. Solve as far as you can on your own, then use the solver to confirm an answer or reveal a single tricky cell so you can spot the pattern you missed. Pair it with our tips and strategy guide to turn each unstick into a lesson.