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Isogram Checker - Online Words Without Repeating Letters

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Isogram Checker

Check if a word or phrase is an isogram — no repeating letters. Start typing or click an example.

Try an example:
Dialogue Subdermatoglyphic Uncopyrightable Hello World

Frequently Asked Questions

An isogram is a word or phrase in which no letter of the alphabet occurs more than once. For example, "Dialogue" has no repeating letters (ignoring case), while "Hello" repeats the letter 'l'.

In word puzzles, "isogram" is often used interchangeably with "heterogram," which specifically means a word with all letters different. Some definitions allow isograms to repeat letters the same number of times (second‑order isograms), but this tool checks for strictly unique letters (heterograms).

By default, our tool removes all non‑alphabetic characters (spaces, punctuation, numbers, etc.) and ignores letter case, which matches the most common definition of an isogram. You can uncheck the options to change this behaviour.

The longest well‑known examples are "subdermatoglyphic" (17 letters) and "uncopyrightable" (15 letters). Longer phrases can also be isograms, such as "The quick brown fox jumps over the lazy dog" — but that's a pangram, not an isogram!

Isograms are popular in code‑breaking games (like Mastermind variants), crossword puzzles, and word search challenges. Finding the longest or most surprising isogram is a common brain teaser.

Yes! Many first names are isograms, like "Ambrose," "Douglas," or "Stephanie" (when ignoring case). Paste your name into the checker to find out!
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