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Letter Frequency Analyzer online
Analyze letter and character frequencies in any text
by
CHUNKY
MUNSTER
MUNSTER
Letter Frequency Analyzer counts every character (or only A–Z if you tick 'Letters only') and shows the result as a sorted bar chart with absolute counts and one-decimal percentages. This character frequency counter scales bars to the most-frequent character, so the shape of the histogram is immediately comparable to a known reference such as the English ETAOIN SHRDLU profile. Use this text histogram tool for linguistic research or simple text analysis.
The classic use case is cryptanalysis of monoalphabetic substitution ciphers - Caesar, Atbash, simple substitutions - where the ciphertext shape mirrors the plaintext language's letter distribution. This text analyzer is also handy for linguistic statistics and sanity-checking that a 'random' string really is uniform. With letters-only off, the symbol frequency analyzer counts any Unicode codepoint, so it works for Greek, Cyrillic, and other non-Latin scripts, providing a detailed letter distribution report.
It is the classical attack on monoalphabetic substitution ciphers (Caesar, Atbash, simple substitution). Compare the histogram of the ciphertext to English letter frequencies - E ≈ 12.7%, T ≈ 9.1%, A ≈ 8.2% - to recover the mapping.
Roughly E 12.7%, T 9.1%, A 8.2%, O 7.5%, I 7.0%, N 6.7%, S 6.3%, H 6.1%, R 6.0%. The mnemonic ETAOIN SHRDLU comes from the top-12 letters in English text.
No. The letters-only filter is the regex /[a-zA-Z]/, so it skips accented letters (é, ñ, ü), digits, punctuation and whitespace. To include them, untick the option and the tool counts every character.
Yes - turn off letters-only and the tool counts every Unicode character, so Greek, Cyrillic or Chinese text produces a real frequency table. Reference distributions exist online for most major languages.
From breaking simple ciphers to analyzing the density of certain characters in your code or writing, this technical utility provides instant, visual feedback. Bookmark this Letter Frequency Analyzer for your next cryptanalysis or text processing task.