What Is a Word Ladder Puzzle?

Published 9 October 2026 · By Gordon Bain

A word ladder — also called a word chain, a doublet, or word golf — challenges you to turn one word into another by changing a single letter at a time. Here's where the idea came from and how it actually works.

The rules, in one sentence

Start on one word, finish on another, and change exactly one letter per step — and every single step along the way has to be a real word too.

A simple example

The classic example is turning CAT into DOG in three moves:

Each step is a real word, and only one letter changes at a time. That's the whole puzzle — the challenge is finding the path.

Where word ladders came from

The format was invented by Lewis Carroll — yes, the Alice in Wonderland author, real name Charles Dodgson. By his own account he came up with the idea on Christmas Day, 1877; the first mention of it in his diary is dated 12 March 1878, where he called it "Word-links." He later renamed it "Doublets" and began publishing a regular series of puzzles under that name in the magazine Vanity Fair, starting with the 29 March 1879 issue, before the series was collected into a book later that year. The CAT-to-DOG example above is one of his own, and it's still the example most commonly used to explain the genre nearly 150 years later (see Wikipedia's history of the word ladder).

Why they're still fun

A word ladder combines two different skills: vocabulary recall, and a bit of forward planning. Unlike a straightforward vocabulary quiz, not every single-letter change leads somewhere useful — sometimes the fastest route to the target word means taking a step that doesn't look like progress at first. That small amount of lookahead is what makes word ladders feel more like a puzzle than a word-recall test.

Not every word can reach every other word

Word ladders are well-defined enough that they've been studied mathematically. Computer scientist Donald Knuth built a graph connecting 5,757 common five-letter English words, linking any two that differ by a single letter. He found that 671 of those words — about one in nine — weren't connected to any other word at all. Knuth called these words "aloof," noting that aloof is itself one of them: there's no other common five-letter word you can reach from it by changing a single letter. It's a neat demonstration of why some word ladders feel impossible — sometimes the word you're starting from genuinely has no path to where you're trying to go.

Word ladders today

Lexaro is a modern, mobile take on the format — a new word chain every day in the Daily Challenge (the same puzzle for every player, worldwide), plus a 250-level campaign spanning five difficulty tiers. See how it works or jump straight to the download links.

Want more? Read how to solve word chain puzzles, or see how word ladders compare to Wordle and crosswords.