answer key switched on
Printable sudoku with answers — puzzles and full solutions in one PDF
Every run can carry its own answer key: the puzzles first, then a matching solution section at the back, each grid labelled with the same ID as the puzzle it solves.
Set a run with answers
answers are switched on here — untick any time
1–60 · each puzzle is solver-checked for a single solution before it goes in
This is a live sample puzzle — it updates to your own puzzles once the run finishes.
How the answer key is laid out
The solutions never share a page with the puzzles. Your PDF runs the puzzle pages first — however many that takes at your chosen layout — and then starts a fresh section headed answer key. That matters if you are handing sheets out: print the document, keep the back half, and nobody is looking at the answer to the grid in front of them.
Matching a solution to its puzzle is done by code. Each puzzle prints a six-character code under its grid, along with its difficulty and how many clues it started with. The corresponding solution prints the same code followed by the word “solution”. Shuffle the pages, split them between two rooms, come back to them a month later — the codes still line up. And if the key goes missing altogether, that code still fetches the answer on the answer lookup page.
The key uses the same layout as the puzzles. Two puzzles per page means two solutions per page; six means six. So if you want solution grids large enough to check quickly, set the layout to one or two per page and the key follows.
Why the printed answer is the right one
The solution is not reverse-engineered from the puzzle after the fact. It is the other way round: the generator builds a complete, valid grid first, and the puzzle is what is left after clues are taken out of it. The answer key you print is that original grid.
The reason there is no second valid answer is the removal rule. After each clue is removed, a solver counts how many solutions the remaining grid has, stopping at two. If it finds two, the clue goes back. So the puzzle you print can only be completed one way, and that way is the key at the back of your PDF.
Sudoku with answers — questions
Where do the answers appear in the PDF?
In their own section after all the puzzle pages, never on the same sheet as the puzzle they solve. That way you can hand out the puzzle pages on their own and keep the key back, and nobody catches an accidental glimpse of the grid they are working on.
How do I match a solution to its puzzle?
Every puzzle is printed with a six-digit ID under its grid, alongside its difficulty and clue count. The matching solution carries the same ID, so "#438201 solution" is the answer to puzzle #438201 no matter how you shuffle the pages.
Can I print the puzzles without the answer key?
Yes — leave "Include answers" unticked and the PDF contains puzzle pages only. That is the default everywhere except this page. You can also generate once with the answers included and simply print the first half of the document, since the answer section always comes last.
Are the answers guaranteed correct?
The solution is not worked out after the fact — it is where the puzzle came from. The generator builds a complete valid grid first, then removes clues from it, so the printed answer key is the original grid. And because a clue is only removed when the puzzle still solves uniquely, that grid is the only answer that fits.
Can I get the answer key at a bigger size?
Set puzzles per page to 1 or 2. The key uses exactly the same layout as the puzzle section, so a one-per-page run gives you full-size solution grids that are easy to check at a glance.
Pick a difficulty for your answer-key set
The answer key works the same at every level, but it earns its place most on the hard and expert grids — where a single wrong entry can hide for forty moves.
- Printable sudoku — easy38–45 cluesGenerous clue counts, no guessing, and a solving path that opens up the moment you start scanning.typical solve: 5–10 minutes
- Printable sudoku — medium30–37 cluesThe everyday sudoku — the level a newspaper prints on a Wednesday.typical solve: 10–20 minutes
- Printable sudoku — hard25–29 cluesSparse grids that will not open up until you start reasoning about where digits cannot go.typical solve: 20–40 minutes
- Printable sudoku — expert20–24 cluesStripped to the bone — around a quarter of the grid filled in, and a single solution waiting at the end of it.typical solve: 40 minutes to over an hour
Back to the free printable sudoku generator or browse all printable sudoku levels.