Word Ladder Generator

How to Use the Word Ladder Generator

1. 1. Enter two words of the same length — cold and warm, say — or pick a word length and a number of steps and press Suggest a pair.
2. 2. Read the answer. The tool finds the shortest ladder, tells you how many steps it takes and how many different ladders of that length exist.
3. 3. Set up the worksheet. Choose a hint level, add spare rungs if you want to allow longer answers, and decide whether to print a name-and-date line.
4. 4. Print or check. Print worksheet gives the puzzle; Print worksheet and key adds the answer page. To mark a student's attempt, paste it into Check a ladder and every rung is tested.

How a Word Ladder Works

A word ladder turns one word into another by changing a single letter at a time, and every word along the way must be a real word. Each change is a step; the words between the start and the end are the rungs. COLD to WARM takes four steps: COLD, CORD, WORD, WORM, WARM. Three rungs, each one letter away from the one before.

Lewis Carroll (Charles Dodgson) invented the puzzle in 1877 and called it Doublets; it ran in Vanity Fair from 1879. His best-known example, "drive PIG into STY", is PIG, WIG, WAG, WAY, SAY, STY — five steps, and still the shortest there is. Teachers use ladders for phonics and spelling patterns, and computer scientists treat them as a graph: words are points, two words are joined if they differ by one letter, and the shortest ladder is the shortest path between two points.

How the Answer Is Found and Checked

Words are checked against ENABLE, a public-domain word list used by many word games, loaded once when you first type. The tool groups words by pattern — COLD fits *OLD, C*LD, CO*D and COL* — so every word one letter away is found instantly, then runs a breadth-first search from the start word. (To solve a ladder without making a worksheet, use the Word Ladder Solver.) Breadth-first search always reaches the end by the fewest possible steps, and counting the routes into each word gives the number of different shortest ladders.

ENABLE is generous. It holds rare words such as ope and bey that a shortest-path search will happily use, and it contains words you would not hand to a class. So the default setting, Prefer everyday words, is not a plain shortest path. For words of two to five letters it uses a hand-picked list of common words, which leaves out crude ones, and treats a step onto any other word as costing four. A ladder may therefore take a step or two more than the true shortest, and the page says so and shows the shortest length. Any unfamiliar rung it still needs is listed, with a button that searches again without it. Check a ladder before you hand it out; the list is a filter, not a guarantee.

Hints, Extra Rungs and Difficulty

• No hints is the classic puzzle: only the start word, the end word and empty boxes.
• Mark the letter that changes draws a heavy box around the one square that changes at each rung — a hint that survives black-and-white printing.
• Fill in every letter except the one that changes turns the ladder into a fill-in-the-blank, the gentlest version for early readers.
• Extra blank rungs give room for a student who finds a longer ladder than the key; the hints follow the key ladder only.
• Difficulty mostly comes from the number of steps and the length of the words: three-letter ladders of three to four steps suit younger pupils, five-letter ladders of six or more steps are a real challenge.

Frequently Asked Questions

What is a word ladder?

A puzzle in which you change one letter at a time to turn a start word into an end word, forming a real word at every step. COLD to WARM, for example, is COLD, CORD, WORD, WORM, WARM. The words in the middle are called rungs.

Who invented word ladders?

Lewis Carroll, the author of Alice in Wonderland, invented the puzzle in 1877 under the name Doublets. It was published in Vanity Fair magazine from 1879, and the idea has since been called word ladders, word golf and laddergrams.

How do I find the shortest word ladder?

Treat every word as a point and join words that differ by one letter, then run a breadth-first search from the start word. It explores all words one step away, then two, and so on, so the first time it reaches the end word is by the shortest route. This tool does that against the ENABLE word list.

Why does the ladder use words I do not know?

Because the word list is large and includes rare words, and a shortest-path search will use them. Leave Prefer everyday words on, then add any word you dislike to Words to avoid, or press the button that appears when the ladder includes an unfamiliar rung. If a ladder is only possible through a rare word, the tool uses it and lists it.

Why does it say my word is not in the word list?

The list has ordinary dictionary words but no proper nouns, abbreviations or most slang, and some variant spellings differ. Try the other spelling, or pick another word. A word being absent from the list does not mean it is not English, only that the puzzle will not accept it.

Can every pair of words be joined by a ladder?

No. Some words have no neighbour at all, and others sit in a small island of words cut off from the rest, so no ladder reaches them. The tool tells you when no ladder exists. Banning a word can also cut a pair off, so check the Words to avoid box if a ladder you expected disappears.

Does the generator send my words anywhere?

No. The word list is downloaded once to your browser and everything else runs on your device. The words you type, the ladders and any class names stay on the page.