How to play Word Ladder

Word Ladder is the oldest word puzzle still in circulation. Lewis Carroll invented it on Christmas Day 1877, called it Doublets, and published it as a weekly column in Vanity Fair the following year. The rules have not needed changing since.

You are given two words. Turn the first into the second by changing one letter at a time, where every step along the way is itself a real word.

Carroll’s own example:

HEAD
HEAL
TEAL
TELL
TALL
TALE

Six words, five steps, and every rung a word in its own right.

The rules

• Change exactly one letter each step. Never two, and never none.
• Never add or remove a letter. Every rung is the same length.
• Letters stay where they are. You cannot rearrange them — HEAD to HADE is not a step.
• Every rung must be a real word from the word list.

Reaching the target word finishes the ladder.

How to play it here

Tap any letter in your current word to choose it, then tap its replacement on the keyboard below. If the result is a word, you climb a rung. If it is not, nothing is lost — you are told why and can try another letter.

You can also just type: pick a letter with a tap or the arrow keys, then press a key.

Undo is unlimited. Press Backspace or use the button.

Scoring, and why every puzzle can be solved

Your score is the number of steps you took, and fewer is better.

Every daily also shows you the shortest ladder that exists for that pair. Finding it is the real challenge; simply arriving is the first one.

Here is the part that matters, because it is where most word ladder puzzles go wrong. Choosing two words at random and hoping there is a path between them produces impossible puzzles, and nobody can tell which days those were — so every score on a broken day is noise, and players blame themselves for a puzzle that had no answer.

These puzzles are built the other way round. The whole word list is treated as a network, where two words are connected when they differ by a single letter. Each daily starts from a word and walks outward through that network to find every word it can reach, then picks the target from the ones sitting four to six steps away.

Two things follow, and both are guarantees rather than hopes:

• A solution always exists, because the puzzle was made by walking one.
• The shortest possible answer is known exactly, which is what lets the game tell you the best score available rather than guessing at difficulty.

There is also no dead end. Wherever you wander, the target is still reachable — so a ladder is never lost, only unfinished, and it is always worth trying a line to see where it goes.

The word list

The list is ordinary English — a couple of thousand common four-letter words. That is a deliberate choice over a full scrabble dictionary, which would connect more words but would route puzzles through terms nobody has ever met. A ladder whose answer depends on a word you have to look up is not a puzzle you lost; it is a puzzle that cheated.

No proper nouns, no abbreviations, nothing crude.

A few pointers

• Work backwards as well as forwards. The target usually has fewer neighbours than your start does, so the last two rungs are often easier to spot than the first two.
• Look at the letters you already share. If your word and the target agree in two positions, those are probably not the letters to touch.
• Vowels are the flexible ones. Changing a vowel usually lands on another word; changing a consonant is where ladders get stuck.
• A step backwards is sometimes the way through. Moving a letter away from the target can open a neighbourhood that the direct route does not reach. The shortest ladder is not always the one that looks most direct at every stage.
• If you are stuck, undo two rungs, not one. Dead ends are usually entered a step before you notice them.