OneTaskBy Tim King · Updated
Sudoku Generator
Printable Puzzles From Easy to Expert, One to Six Per Page, With Keys
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If this tool saved you time, a coffee helps keep new ones coming.
How the Sudoku Generator works
This sudoku generator makes fresh, printable sudoku puzzles at four difficulty levels. Pick how many you want on a page, press Print, and tick "Show answers" for a matching answer key. Every puzzle has exactly one solution.
How the sudoku generator grades difficulty
Each puzzle starts as a full, random, valid grid. Squares are then removed in matching pairs, keeping the pattern symmetrical, and after each removal the generator checks that only one solution remains. Easy and Medium puzzles can always be finished with singles, the two basic techniques of finding the only digit a square can hold or the only square a digit can go in. Hard and Expert puzzles have fewer clues and need more advanced reasoning.
Clue counts
Easy puzzles keep around 38 clues, Medium around 31, Hard around 27 and Expert as few as the generator can reach while staying unique, usually 24 to 26. Fewer clues are not always harder, which is why the generator also checks which techniques the puzzle needs.
Printing
Choose one puzzle for a large grid, or four or six for a booklet page. The Print button sends only the title, name line and puzzles to the printer. Print a second copy with answers shown for marking.
FAQ
Is every puzzle guaranteed to have one solution?
Yes. After removing each pair of clues, the generator runs a full solver to count solutions and puts the clues back if a second solution appears. A puzzle with more than one answer is never shown.
Why does Expert sometimes take a moment?
Expert puzzles need several attempts to find a grid that is unique, low on clues and too hard for singles alone. Each attempt runs the solver many times, so a page of six Expert puzzles can take a second or so on a slower device.
Can I get the same puzzles again?
The puzzles stay the same until you press New puzzle or change a setting, so you can print the puzzle sheet and then the answer key without losing them. Reloading the page starts a fresh set.
See also: all Puzzle Makers tools, Scrabble & Board Games, Puzzle Solvers, Anagrams & Rhymes.
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