Printable Sudoku Generator

Who ends up printing these

• Primary and high school teachers who want a settling activity for the first five minutes of a lesson, printed two to a page to halve the paper bill.
• Aged care and community centre staff putting together a weekly activity sheet.
• Self publishers assembling a puzzle book. The guide on making a puzzle book to sell on KDP covers trim sizes, page counts and interior layout.

How each puzzle is built

Nothing here is pulled from a stored library. Every grid is made on the spot, in four steps.

1. An empty 81 cell grid is filled by a backtracking solver. It walks to the first blank cell, tries the digits 1 to 9 in a freshly shuffled order, keeps any digit that breaks no row, column or box rule, and backs up when it reaches a dead end. Shuffling at every step is what makes each completed grid different.
2. A target number of clues is chosen at random from the range for your chosen difficulty.
3. The 81 positions are shuffled, and the tool walks that list removing digits until the clue count reaches the target.
4. For easy and medium, each removal is tested before it is kept. A counting solver runs on the partly emptied grid and stops the moment it finds a second answer. If two answers exist, the digit goes back and the next position is tried.

What the difficulty setting really controls

Difficulty here is the number of starting clues, not an analysis of which solving techniques a puzzle demands. Easy leaves 38 to 45 clues, medium 30 to 36, and hard 25 to 28. Fewer clues generally means more work, though it is a rough guide: a 32 clue puzzle can occasionally fall out faster than a 40 clue one depending on where the clues sit. Hard puzzles skip the uniqueness check, because verifying every removal at that clue count is slow in a browser, so a hard grid may in rare cases have more than one valid answer. The solution shown is always a correct one.

An example run

Select Medium and press New puzzle. After a moment the grid appears and the status line reports a medium puzzle with, say, 33 clues, and confirms that a single answer was verified. Press Show solution and the missing digits appear in a lighter colour so you can check an answer without reprinting. Choose the two per page layout, press Print, and you get a sheet with two grids followed by a separate answer page. Download PNG saves the blank grid as sudoku.png, and the second button saves the filled grid as sudoku-solution.png.

Printing, styling and the watermark

Print output is built for paper: black digits on white, heavy 3 by 3 box borders, one or two grids per page, and an answer page after them. The style panel adds thirteen background themes, six print safe font stacks, an opacity slider and a title of your own. Free printouts and PNG exports carry a light ZillaKit.com watermark across the grid and a small credit line underneath; the puzzles are free for personal and classroom use. Premium removes the watermark, allows your own background image, and adds the commercial licence needed if the puzzles are going into a product you sell.

What this page will not do

The on screen grid is for previewing and printing, not for playing: the cells are not editable, so there is nowhere to type a digit or to pencil in candidates. It does not solve a puzzle you already have, and it offers no 4 by 4, 6 by 6 or 16 by 16 variants, killer or diagonal rules. Everything happens in your browser and nothing is uploaded to a server. Generating puzzles costs nothing; once your credit is used up a brief rewarded ad appears before the next one.

Other printable puzzle makers

For word puzzles rather than numbers, try Word Search Maker or the multi puzzle Word Search Book Maker, and Crossword Maker for clue based grids. Maze Generator suits younger children and Bingo Card Maker suits groups. Readers who need bigger type can use Large Print Maker, and a finished book interior can be set with Paperback Typesetter. Handwriting sheets come from Handwriting Practice.

Questions about the generator

Does every puzzle have exactly one answer?

Easy and medium puzzles are checked after every clue is removed, and a removal that would allow a second answer is undone, so those grids have a single solution. Hard puzzles skip that check for speed, so a small number of them may accept more than one answer.

How many clues does each difficulty leave?

Easy keeps 38 to 45 clues, medium 30 to 36, and hard 25 to 28. The exact figure is picked at random inside the range and shown in the status line under the controls.

Can I solve the puzzle on screen?

No. The grid is a preview for printing or exporting, and the cells cannot be typed into. Print it, or save the PNG and write on it in a drawing app.

Is there a watermark on what I print?

Yes on the free tier. Printouts and PNG exports carry a faint ZillaKit.com mark over the grid and a small credit line. Premium removes it and includes the licence needed to sell or publish the puzzles.

Can I sell books made with these puzzles?

Only with the premium commercial licence. Free use covers personal, family and classroom printing.

Will it solve a Sudoku I already have?

No. This page only creates new puzzles. There is no way to enter an existing grid and have it worked out for you.