Word Ladder

Word Ladder is the 1879 puzzle invented by Lewis Carroll (author of Alice in Wonderland) — he originally called it “Doublets.” Start with one word; change one letter at a time to form new valid words; end at a target word. Each intermediate word must be a real word. Word Ladder tests vocabulary, pattern matching, and lateral thinking.

How to play

• You’re given a starting word and target word, both of the same length.
• Change ONE letter to form a new valid word.
• Each step must be a word in the game’s built-in word list, and you can’t reuse a word.
• Continue until you reach the target.
• Goal: minimize the number of steps. The Min counter shows the shortest possible ladder, and your best for each puzzle is saved in this browser.
• Stuck? Hint suggests the next word on a shortest path, and Undo removes your last word.

Example

WHEAT → CHEAT → CLEAT → BLEAT → BLEAK → BREAK → BREAD. Wheat to bread in 6 steps, the shortest ladder for that puzzle here. Lewis Carroll’s own classic: HEAD → HEAL → TEAL → TELL → TALL → TAIL.

Beginner strategy

• Look at letter differences. If start and target differ in 4 letters, you need at least 4 changes.
• Each change must be valid. Don’t change a vowel to a consonant arbitrarily.
• Common word patterns. Everyday 5-letter words like CHEAT, CLEAR and STONE are the safest bets for the word list.
• Vowel chains. Change a vowel to another valid word; then change consonants.
• Reverse engineer. Start from the target and work backward.

Word Ladder math

• Search space. Each word is a node, and words one letter apart are linked. Our word list holds about 4,500 common 4- and 5-letter words, and every puzzle is checked to have a ladder through it.
• BFS algorithm. Breadth-first search finds shortest paths in the word graph. It’s how the game works out the Min value and its hints.
• Easy for computers. Finding a shortest ladder is a quick shortest-path search, even across a full dictionary.

FAQ

• Q: Who invented Word Ladder? A: Lewis Carroll in 1879. Originally called “Doublets.”
• Q: Can I use any English word? A: Only words in the game’s built-in list of common words. Rare words, names and abbreviations aren’t accepted.
• Q: Minimum steps? A: At least the number of letter positions that differ between start and target.
• Q: Famous example? A: Carroll’s HEAD → TAIL in 5 steps. He also set puzzles such as WHEAT into BREAD and FOUR to FIVE.

For other word games, try Anagram, Wordle, Word Scramble, or Word Search.