Letter Frequency Counter & Analysis
Count how often each letter appears, compare with English letter frequencies, and get the index of coincidence, top bigrams and a Caesar-shift hint for cipher solving.
🔒 Runs entirely in your browser — nothing is uploadedCount every letter in your text
A letter frequency counter shows how often each character appears in a text, as a count and as a percentage, with a bar chart that makes the distribution easy to read. Writers use it to check a lipogram or a pangram, word-game players to study letter distributions, teachers to show students how language works, and puzzle and cryptography fans to attack ciphers. Results update as you type and can be sorted by frequency or alphabetically; the table can be copied as CSV or Markdown with the buttons above it.
By default the tool counts the letters A to Z without regard to case. Untick "A–Z only" to count every Unicode letter, including é, ß, ł, Cyrillic and Greek, and optionally digits and punctuation. Tick "Case sensitive" to count capitals separately.
Frequency analysis for ciphers
Frequency analysis is the oldest code-breaking technique, described by the Arab scholar al-Kindi in the 9th century. In a simple substitution or Caesar cipher each letter is always replaced by the same symbol, so the most common ciphertext letter probably stands for E, the next for T or A, and so on. Each bar in the chart has a marker showing the letter's typical share in English, so mismatches stand out immediately.
Three extra statistics help with harder puzzles. The index of coincidence tells you whether letter frequencies are still English-like (around 0.067) or flattened toward random (around 0.038), which points to a polyalphabetic cipher such as Vigenère. The top bigrams list common two-letter pairs; in English, TH, HE, IN and ER lead. The likely Caesar shift tests all 26 shifts and reports the one whose frequencies best fit English. The example text is a Caesar cipher with a shift of 3 — try decoding it with the Caesar Cipher tool.
Private analysis
All counting and statistics run in your browser. Puzzle answers, manuscripts and messages are never uploaded.
How to use
- Paste text or ciphertextAdd any text, puzzle or encrypted message.
- Set what to countCount A–Z only or every letter, and optionally digits and punctuation, with or without case sensitivity.
- Read the histogramCompare each letter's share with typical English frequencies, shown as a marker on every bar.
- Use the cipher hintsCheck the index of coincidence, top bigrams and the most likely Caesar shift.