// Text / Analysis
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. The bars are scaled 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.
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. It is also handy for linguistic statistics and sanity-checking that a 'random' string really is uniform. With letters-only off the analyser counts any Unicode codepoint, so it works for Greek, Cyrillic and other non-Latin scripts.
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.
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