What counts as a word ladder?

A chain of real words from a start word to an end word where each rung differs from the one before it in exactly one letter, and the letters stay in place: no anagrams, no adding or dropping letters. CAT to DOG is the classic, and the shortest chain in this dictionary is CAT, COT, COG, DOG, three steps. Because the length never changes, both of your words have to be the same length, which is why a pair like CAT and HOUSE is refused with a message rather than searched.

Is the ladder it shows really the shortest one?

Yes, within the word list it searched. The solver runs a breadth-first search, which finishes a whole layer of words before moving to the next, so the first time the chain from your start word meets the chain growing back from your end word, that meeting is at the shortest possible distance. Two searches meeting in the middle is also far cheaper than one long search, which is why the answer comes back immediately. Where several different chains tie for shortest, the page shows one of them, and the same pair always returns the same one.

Why does it sometimes say there is no ladder?

Because for many pairs there genuinely is none in this dictionary. A word ladder needs a path of real words at every step, and plenty of words have no neighbour at all: EVIL, for instance, is a four-letter word that no other four-letter word in ENABLE sits one letter away from, so nothing can reach it. The page says there is no ladder in this word list, and names the list, which is the honest claim. A bigger dictionary, or one that allows proper nouns, could connect a pair this one cannot.

Which dictionary is used, and is it a game's official list?

ENABLE, the Enhanced North American Benchmark Lexicon: 172,823 words, public domain, and the list a large share of word games are built on. It is the same file the anagram solver, the Wordle solver and the Spelling Bee solver on this site already use, so it costs no extra download if you have used one of those. It is not any particular game's official word list, so a rung here can be a word your game rejects, and a word your game allows can be missing here.

Why is it limited to words of 3 to 7 letters?

This tool supports words from three to seven letters in ENABLE. Short words tend to have more one-letter neighbours; connections become sparser as words get longer. Longer words can also form ladders, but they are outside this solver's supported range. A result describes the words and connections in this dictionary, rather than every possible English word.

What does the Avoid box do?

It takes words the ladder is not allowed to step on, separated by spaces or commas, and the search is run again without them. That is how you get the second route when two are the same length, or work around a rung a puzzle has already used. Excluding a word that the list does not hold at that length changes nothing, so the page lists those back to you instead of leaving you to wonder, and a word you excluded that is also your start or end word is refused with a message saying which one to change.

Does anything I type get uploaded?

No. The page makes one request, to this site, for the word list, and it makes that request when you first solve rather than when the page loads, so reading the page costs nothing. Your two words are matched against the list inside your browser, so there is no search history to keep and nothing to send. Once the list is in memory the solver carries on working with the network switched off, and the words you typed are remembered only in this browser so the page opens where you left it.

Why does the first search download a file, and how big is it?

Because a ladder needs a dictionary at every rung, and this tool has no server to hold one. The ENABLE list is 1.7 MB of plain text, fetched the first time you ask for a ladder and then held for the rest of the session, so later searches take milliseconds. The words of each length are indexed once by pattern, which is what makes a second search of the same length instant. If the download fails, the page says so and offers Try again rather than showing an empty result that could be mistaken for a real answer.

Can I request exactly four, five, six or seven steps, or enter clues?

The solver finds a shortest chain and reports its step count. There is no exact-length control, clue input or required-letter pattern. A shortest result might have the requested count for a particular pair, but the page does not search for a longer chain of a chosen length. Avoid only removes specified words; it does not impose an exact number of steps.

Is this a Python word-ladder solver package?

This is an interactive browser solver with a downloaded word list and copyable chain. It does not provide an installable Python package or a Python code implementation.

Word Ladder Solver

Enter From and To words of the same length, from 3 to 7 letters, and choose Solve. The result shows a shortest chain in the finite ENABLE word list and highlights each changed letter. Avoid excludes unwanted rungs. Steps count letter changes, while Words includes both endpoints. A stopped search is reported separately from a completed no-ladder result.

Climb from one word to another

Two words of the same length, and the shortest chain that changes one letter at a time appears, every rung a real word.

All 172,823 ENABLE wordsSearched in your browserNo account, nothing uploadedShortest route, or none at all

No ladder is on the stage yet. Type two words of the same length, 3 to 7 letters.

From

Avoid

Steps

not yet

Words

Length

3 to 7

List

ENABLE

Both words need the same length, 3 to 7 letters, and every rung has to be a word in the ENABLE list, 172,823 words of public domain English. The list, 1.7 MB, downloads once when you first solve, and every search after that runs in this browser. Several chains often tie for shortest: this shows one of them, and the same pair always gives the same one.

Three cases worth trying

Choose one to load it into the fields above.

COLD to WARM4 letters
4 steps
EVIL to GOODsame length, no route
says none exists in this list
CAT to HOUSE3 letters and 5
refused, lengths differ

How the search works. Every word of the right length is filed under the patterns it matches, so COLD sits under _OLD, C_LD, CO_D and COL_. Two words share a pattern exactly when they are one letter apart, which turns neighbours into a lookup rather than a comparison against every word. The search then grows one chain out from your start word and another back from your end word, expanding the smaller side each round until they meet in the middle. Expanding a whole layer before looking for that meeting is what makes the ladder the shortest, rather than merely a short one.

Accuracy. A breadth-first search, so the ladder it returns is genuinely the shortest one that exists in the word list it uses. That list is ENABLE, which is finite: a pair with no ladder here may have one in a larger dictionary, and the page says that rather than claiming none exists.

Common questions

What counts as a word ladder?: A chain of real words from a start word to an end word where each rung differs from the one before it in exactly one letter, and the letters stay in place: no anagrams, no adding or dropping letters. CAT to DOG is the classic, and the shortest chain in this dictionary is CAT, COT, COG, DOG, three steps. Because the length never changes, both of your words have to be the same length, which is why a pair like CAT and HOUSE is refused with a message rather than searched.
Is the ladder it shows really the shortest one?: Yes, within the word list it searched. The solver runs a breadth-first search, which finishes a whole layer of words before moving to the next, so the first time the chain from your start word meets the chain growing back from your end word, that meeting is at the shortest possible distance. Two searches meeting in the middle is also far cheaper than one long search, which is why the answer comes back immediately. Where several different chains tie for shortest, the page shows one of them, and the same pair always returns the same one.
Why does it sometimes say there is no ladder?: Because for many pairs there genuinely is none in this dictionary. A word ladder needs a path of real words at every step, and plenty of words have no neighbour at all: EVIL, for instance, is a four-letter word that no other four-letter word in ENABLE sits one letter away from, so nothing can reach it. The page says there is no ladder in this word list, and names the list, which is the honest claim. A bigger dictionary, or one that allows proper nouns, could connect a pair this one cannot.
Which dictionary is used, and is it a game's official list?: ENABLE, the Enhanced North American Benchmark Lexicon: 172,823 words, public domain, and the list a large share of word games are built on. It is the same file the anagram solver, the Wordle solver and the Spelling Bee solver on this site already use, so it costs no extra download if you have used one of those. It is not any particular game's official word list, so a rung here can be a word your game rejects, and a word your game allows can be missing here.
Why is it limited to words of 3 to 7 letters?: This tool supports words from three to seven letters in ENABLE. Short words tend to have more one-letter neighbours; connections become sparser as words get longer. Longer words can also form ladders, but they are outside this solver's supported range. A result describes the words and connections in this dictionary, rather than every possible English word.
What does the Avoid box do?: It takes words the ladder is not allowed to step on, separated by spaces or commas, and the search is run again without them. That is how you get the second route when two are the same length, or work around a rung a puzzle has already used. Excluding a word that the list does not hold at that length changes nothing, so the page lists those back to you instead of leaving you to wonder, and a word you excluded that is also your start or end word is refused with a message saying which one to change.
Does anything I type get uploaded?: No. The page makes one request, to this site, for the word list, and it makes that request when you first solve rather than when the page loads, so reading the page costs nothing. Your two words are matched against the list inside your browser, so there is no search history to keep and nothing to send. Once the list is in memory the solver carries on working with the network switched off, and the words you typed are remembered only in this browser so the page opens where you left it.
Why does the first search download a file, and how big is it?: Because a ladder needs a dictionary at every rung, and this tool has no server to hold one. The ENABLE list is 1.7 MB of plain text, fetched the first time you ask for a ladder and then held for the rest of the session, so later searches take milliseconds. The words of each length are indexed once by pattern, which is what makes a second search of the same length instant. If the download fails, the page says so and offers Try again rather than showing an empty result that could be mistaken for a real answer.
Can I request exactly four, five, six or seven steps, or enter clues?: The solver finds a shortest chain and reports its step count. There is no exact-length control, clue input or required-letter pattern. A shortest result might have the requested count for a particular pair, but the page does not search for a longer chain of a chosen length. Avoid only removes specified words; it does not impose an exact number of steps.
Is this a Python word-ladder solver package?: This is an interactive browser solver with a downloaded word list and copyable chain. It does not provide an installable Python package or a Python code implementation.

A breadth-first search, so the ladder it returns is genuinely the shortest one that exists in the word list it uses. That list is ENABLE, which is finite: a pair with no ladder here may have one in a larger dictionary, and the page says that rather than claiming none exists.