How to play sudoku
Fill in the grid so that every row, every column and every 3 by 3 box has the numbers 1 to 9, each used once. The numbers already printed in the grid are your starting clues. You never need arithmetic: the numbers are just nine different symbols.
Start with the row, column or box that has the most numbers filled in, and ask which numbers are still missing. When only one square can take a number, write it in. Each number you place gives you new clues for the squares around it.
What each level asks of you
The levels here are set by the hardest step a puzzle needs, not by how many numbers it gives you. A puzzle with few clues can still be easy if every step is a simple one.
| Easy | Singles only: look for the one place a number can go, or the one number a square can hold. |
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| Medium | Still singles, with about ten fewer numbers given, so each one takes longer to find. |
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| Hard | Pointing numbers, naked and hidden pairs, and naked triples. |
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| Expert | Everything in the hard set, plus an X-wing or an XY-wing. No guessing is ever needed. |
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Tips for harder puzzles
Use pencil marks. In each empty square, write small the numbers it could still hold. Hard and expert puzzles cannot really be solved without them.
Look for pairs. If two squares in a row can only hold the same two numbers, those numbers must go in those two squares, so you can rub them out everywhere else in that row.
X-wing. If a number can go in only two squares in each of two rows, and those squares line up in the same two columns, the number cannot go anywhere else in those columns.
Questions
Are these sudoku puzzles free to print?
Yes. All 48 puzzles and their answer keys are free to print at home, with no signup and no watermark.
Does every puzzle have only one solution?
Yes. Each puzzle is checked by a solver before it goes on the page, and any grid with more than one solution is thrown out. The answer key is the only way the grid can be filled.
Do I ever have to guess?
No. Every puzzle here, including the expert set, can be solved by logic alone. The hard and expert puzzles need pencil marks, but never a guess.
How are the levels decided?
By the hardest step you need, not by how many numbers are given. Easy and medium puzzles need only singles. Hard puzzles need pairs and triples. Expert puzzles need an X-wing or an XY-wing.
Are these large print?
The single-puzzle PDFs print one grid to a page, about 6.7 inches wide, with numbers roughly a quarter inch tall. The four-to-a-page PDFs are smaller and save paper.
Where are the answers?
Each single puzzle has its answer on page 2 of the same PDF. The level packs put all the answers on the last pages.
