Tattarrattat, twelve letters, is the longest palindrome the Oxford English Dictionary holds. This tool checks any word, phrase or number for symmetry, names the exact position where it breaks, and draws examples from 66 verified palindromes.
Palindrome names, and how many of them exist
Tattarrattat, twelve letters, is the longest palindrome the Oxford English Dictionary holds. This tool checks any word, phrase or number for symmetry, names the exact position where it breaks, and draws examples from 66 verified palindromes.
Palindrome names come from their own pool here, kept separate from the other three sets because somebody hunting a phrase for a crossword does not want three-letter first names. Every entry was verified by running it back through the checker on this page rather than by eye, which is not a formality: published palindrome lists routinely carry entries that fail once you strip the punctuation properly. Draws are random and without replacement, so asking twice gives a different selection, and asking for more than the pool holds returns the whole pool with a note saying so. The checker half of the tool is separate and works on anything at all, so if a candidate of your own is not on the list you can test it and see the exact position where the symmetry breaks.
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Tattarrattat is twelve letters long and it is the longest palindrome in the Oxford English Dictionary
James Joyce made the word up in Ulysses for the sound of a knock at a door, and it has been in the dictionary ever since. Everything shorter that people usually reach for sits well under half that length: racecar at seven, level at five, deed at four. This tool does two separate jobs. It takes anything you type, strips the capitals, spaces and punctuation, and tells you whether what is left is symmetrical, naming the exact position where it stops being symmetrical if it does. And it draws examples from 66 palindromes held in four sets, so you are not staring at a blank field trying to remember one.
From input to verdict, in five steps
- Mode - Check one tests what you type and nothing else. Draw examples ignores the text field entirely. Check one and draw examples does both in one run, which is the setting most people want.
- Word, phrase or number - anything goes in here. Capitals,
spaces, commas and apostrophes are removed before the comparison, so Madam, I'm Adam
is judged as the eleven characters
madamimadam. - How many examples - from 1 to 20. If the set you picked holds fewer than that, you get all of it and the output says so rather than handing back a short list without explanation.
- Which kind - single words, names and places, phrases and sentences, numbers, or all four mixed together. The filter exists because somebody hunting for a crossword phrase does not want three-letter first names.
- Read the verdict - a yes tells you how many character pairs matched. A no names the first position that broke and counts how many pairs disagree in total, so you can check the answer by hand instead of taking it on trust.
What counts as the same backwards
A palindrome is anything that reads identically in both directions, but almost every interesting example
only qualifies after you agree to ignore some of what is written. A man, a plan, a canal,
Panama has four commas and five spaces in it; drop them, drop the capitals, and
21 letters remain that mirror perfectly around the central c. Keep the
punctuation and the same sentence fails on the first character. That convention is not a shortcut, it is
the standard definition, and it is what this tool applies.
Digits are kept for the same reason letters are. A checker that quietly drops them and then reports the input as too short is answering a question nobody asked, because 12321 is a palindrome under any definition anyone uses. Here a number is treated exactly like a word: 2002 passes, 2003 fails at the first position, and the readout tells you which position that was.
What the tool will not do is invent a palindrome for you. There is no algorithm that produces Rats live on no evil star from nothing, because being a palindrome and being a sentence are two constraints that no generator satisfies at once by luck. What you get instead is a drawn sample from a list where every entry has been verified against the checker itself.
How many palindromes could exist at each length
Half of a palindrome fixes the other half, so the count of possible patterns depends only on the first half. For a 26-letter alphabet that gives 26 raised to the length rounded up and halved, which is why lengths five and six have exactly the same number of patterns. These are letter patterns, not words in any dictionary. Almost all of them are unpronounceable.
| Length | Pattern | Possible patterns | Real example |
|---|---|---|---|
| 3 | aba | 676 | Ada, Bob, Eve |
| 4 | abba | 676 | noon, deed, sees |
| 5 | abcba | 17,576 | level, radar, civic |
| 6 | abccba | 17,576 | redder, Hannah |
| 7 | abcdcba | 456,976 | racecar, deified, repaper |
| 11 | 6 free letters | 308,915,776 | detartrated, Wassamassaw |
| 12 | 6 free letters | 308,915,776 | tattarrattat |
What is in the four sets
| Set | Entries | Shortest | Longest | Use it for |
|---|---|---|---|---|
| Single words | 24 | 4 | 12 | Spelling lessons, crossword fills |
| Names and places | 14 | 3 | 11 | Naming a character, quiz rounds |
| Phrases and sentences | 16 | 11 | 51 | Puzzle clues, epigraphs, party tricks |
| Numbers | 12 | 3 | 6 | Test data, dates, maths classes |
Lengths in that table are counted after normalising, which is why the longest phrase reads as 51 characters even though it runs to sixty-nine with its spaces and full stops. Ask for twenty numbers and you will get twelve, because twelve is all there is.
Six things worth knowing about palindromes
Who opens a tool like this
Puzzle setters and crossword solvers need a phrase of a given length that survives being read backwards, and they need it now rather than after twenty minutes of staring. The phrase set exists for exactly that.
Primary and secondary teachers use palindromes to teach letter order and symmetry, and the four sets let a lesson move from three-letter names up to a fifty-one character sentence without changing tools.
Programmers write a palindrome check in their first week of any language and then need test cases for it: an even-length one, an odd-length one, a phrase with punctuation, a number, and something that fails at a known position. The verdict here names that position, so it doubles as an expected value.
Writers and quiz hosts want the well-known ones spelled correctly, which is harder than it sounds when the sentence is fifty characters long and one dropped letter destroys it.
Questions people ask
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Generator verified by the LiczGrupa.pl team
Content, formulas and results have been reviewed for accuracy and relevance by our team of specialists.
Reviewed by: Krystian Szyszka