Printable Wordoku Puzzles

What’s in the printable Wordoku PDFs?

Each of the four PDFs holds 100 Wordoku puzzles. Wordoku is sudoku with nine letters in place of the digits 1 to 9: every row, every column and every 3×3 box holds each letter once. The nine letters are those of a word, so they change with the word, and the word is hidden on the diagonal from the top-left corner to the bottom-right. Every file runs to 63 US Letter pages:

• page 1, a cover with the rules;
• pages 2 to 51, the puzzles, two to a page, each with its nine letters printed underneath in alphabetical order (“Letters: A D E L M O S T U”);
• pages 52 to 63, the answers, nine to a page.

The pages are black and white, and each file is about 400 KB. The puzzles come from the same generator as our Wordoku game, which picks each word from a list of 123 English words with nine different letters. The 400 printed puzzles use 121 of them, so some words come round more than once: CLOUDIEST is the word of six Easy puzzles.

How hard is each Wordoku level?

The levels differ in how many letters you start with, and in the steps solving takes. We measured the steps on the printed puzzles themselves, with a solver that tries the standard moves in order of difficulty (singles, locked candidates, naked pairs and triples, the X-Wing) and records the hardest one each puzzle needed:

All 100 puzzles of each PDF, exactly as printed, counted by the hardest step each one needed. Nothing needed more than a naked pair, and the generator’s own solver, which shares no code with ours, agrees on every puzzle.

Easy and Medium need nothing but singles. A naked single is a square with one letter left; a hidden single is a letter with one square left in its row, column or box. What separates the two levels is the start, 40 letters against 32. Hard adds locked candidates on one puzzle in eight, and Expert, from 22 to 25 letters, needs them or a naked pair on almost a third. The Wordoku game page draws a hidden single, locked candidates and a naked pair on real boards, in letters.

Where is the hidden word, and should you guess it?

The word runs down the diagonal from the top-left square to the bottom-right, in reading order. The generator writes it there first and fills the grid in around it, so every answer page spells it on that line. A few of its letters are usually given (a median of four on Easy and Medium, three on Hard and Expert), and the temptation is obvious: think of the word, and nine squares fill at once.

On paper, prove the word before you write it in. Nothing on the sheet tells you whether a guess is right, and a wrong letter on the diagonal spreads to everything built on it. Our list holds two words with the same nine letters, CENTROIDS and DOCTRINES, and both are in the Medium PDF: DOCTRINES is Puzzle 62, and Puzzle 29 is CENTROIDS with no diagonal letter given at all.

Once one diagonal square is proved, the word usually follows, and then it earns its place: with the diagonal filled in, singles alone finish 398 of the 400 puzzles. Every word on the list has nine different letters, so the diagonal also holds each letter once. That is sound to use and never needed; rows, columns and boxes finish every puzzle on their own.

Does every puzzle have exactly one answer?

Yes, and each was checked before it was printed. We dealt the puzzles with the generator behind the online game, on fixed seeds, so the same command rebuilds the same four files. Then a counter written separately from the generator searched every puzzle for a second answer. For this page we counted all 400 again with a second counter from our measuring tools, and ran the step solver from the table over each.

The sheets that were here before October 2026 were not made this way. An older script took letters out to a fixed count and never checked what was left, so nothing guaranteed a single answer, and every cover printed a stray “\001” in its title. The four new files replaced them at the same addresses; if you printed a set before, print it again.

How do you print Wordoku puzzles?

• Paper size. The files are US Letter. On A4, choose Fit to page (or Shrink to fit) in the print dialog; they come out at about 97%.
• Only the pages you need. Puzzle n is on page (n + 3) ÷ 2, rounded down: pages 2–6 hold Puzzles 1–10, and pages 2–51 all 100.
• Room for notes. Each grid is 4.1 inches wide, so a square is just under half an inch (about 11.6 mm): room for a few small letters in its corners. Keep pencil marks small and the centre free for the answer.
• Ink. Everything is black and white, with nothing shaded, so a plain mono printer does as well as any.
• Answers. Leave pages 52–63 off a handout and print them separately, so nobody solves with the key in view.

How do you check your Wordoku answers?

Three ways, from quickest to surest:

1. Read the diagonal. If it is not a word, a square on it is wrong. If it is, you have checked 9 squares of 81.
2. Check the rules. Every puzzle has exactly one answer, so a full grid that keeps the printed letters and holds each letter once in every row, column and box is the answer. You can mark your own sheet without the key.
3. Compare with the answer page. Puzzles 1–9 are on page 52, 10–18 on page 53, and so on, nine to a page, to Puzzle 100 on page 63. The given letters are in bold there, so you only compare the letters you wrote.

The second check is the one worth teaching. It is how a solver knows they are right without being told, and it works only because each puzzle has one answer.

Can you use Wordoku in class?

Give everyone the same puzzle number, so the answers can be gone through together, and start on Easy or Medium: both need only singles, and “where can the T go in this box?” is the whole lesson. Ask pupils to say why a letter goes where it does rather than just write it in; a hidden single is easy to justify aloud.

The word makes a better finish than a start. Have the class write it out once the grid is done, and use Medium Puzzle 29 to show why guessing it early is a gamble: its letters spell CENTROIDS and DOCTRINES, and only the grid can say which. The PDFs are free to print for home, class or a club, as many copies as you need; if you share them online, please link to this page rather than uploading the files elsewhere.

Where to go next

The Wordoku game deals a fresh board at any level whenever you like, and the Daily Wordoku deals one a day, the same for everyone. For a Wordoku from a newspaper or a book, the Wordoku Solver solves one you type in. Letter Sudoku and Alphabet Sudoku are the same puzzle without a word, always A to I or nine letters drawn at random, and the printable sudoku page has PDFs of classic sudoku and nine other kinds, from 4×4 to Samurai.