How to use the Letter Frequency Counter
Analyse letter frequency in three steps:
1
Paste your text
Paste any text into the input area. Letter frequencies update in real time as you type.
2
Choose view and sort
Switch between Table view (letter, count, %, inline bar) and Chart view (26-bar chart for all letters). Sort by frequency or alphabetically. Enable 'Show English benchmark' to overlay standard English frequencies.
3
Export results
Click 'Copy TSV' to copy the frequency table as tab-separated values, or download it as a .tsv file for use in spreadsheets.
When to use this tool
Use for linguistic analysis, cryptography, and text statistics:
- →Performing frequency analysis on Caesar cipher or simple substitution cipher ciphertext to identify likely letter mappings
- →Studying letter distribution patterns in text samples from different languages or authors
- →Checking whether a text sample's letter distribution matches expected English frequency (ETAOIN SHRDLU order)
- →Educational cryptography exercises where students learn frequency analysis as a cipher-breaking technique
- →Analysing whether a piece of writing unusually avoids certain letters — for example, a lipogram that omits the letter 'e'
- →Generating letter frequency statistics for linguistic research, readability analysis, or NLP feature engineering
Frequently asked questions
Q:Are uppercase and lowercase letters counted separately?
By default, all letters are converted to lowercase before counting, so 'A' and 'a' are counted together as a single 'a' entry. Enable 'Case sensitive' to count uppercase and lowercase letters as separate entries — in this mode 'A' and 'a' appear as distinct rows in the frequency table. Case-insensitive mode is the standard approach for most frequency analysis tasks.
Q:What is the English benchmark and how does it help?
The English benchmark is the well-established statistical distribution of letters in typical English text. The most frequent letter is 'e' at approximately 12.7%, followed by 't' at 9.1%, 'a' at 8.2%, 'o' at 7.5%, and so on. When the benchmark is enabled, the bar chart shows a grey bar (English average) alongside each letter's coloured bar (your text), and the table adds an 'English %' column. This comparison instantly reveals if your text's distribution deviates significantly from expected English — essential for frequency-analysis-based cipher breaking.
Q:What is frequency analysis and why is it useful for ciphers?
Frequency analysis is a cryptanalysis technique based on the fact that different letters appear at predictable rates in natural language text. In a substitution cipher (where each letter is consistently replaced by another), the most frequent character in the ciphertext likely corresponds to 'e' in the plaintext, the second most frequent to 't', and so on. By comparing the ciphertext's letter distribution to the English benchmark using this tool, you can make educated guesses about letter mappings and progressively decode the message.
Q:What is the difference between Table and Chart view?
Table view shows a sortable data table with each letter, its count, its percentage of total letters, an optional English benchmark percentage column, and an inline proportional bar. It can be sorted by frequency (most to least common) or alphabetically (a to z). Chart view shows all 26 letters as a side-by-side bar chart with fixed alphabetical order — good for seeing the overall distribution shape and identifying which letters are completely absent from the text.
Q:What letters appear most frequently in English?
The standard English letter frequency order from most to least common is: 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%), D (4.3%), L (4.0%), C (2.8%), U (2.8%), M (2.4%), W (2.4%), F (2.2%), G (2.0%), Y (2.0%), P (1.9%), B (1.5%), V (1.0%), K (0.8%), J (0.2%), X (0.2%), Q (0.1%), Z (0.1%). The mnemonic 'ETAOIN SHRDLU' covers the 12 most frequent letters.
Q:Can I export the frequency data to a spreadsheet?
Yes — click 'Copy TSV' to copy the full frequency table as tab-separated values (letter, count, percentage) to your clipboard, ready to paste into Excel, Google Sheets, or Numbers. Click the download button to save it as a .tsv file directly. TSV format is natively recognised by all major spreadsheet applications without any import configuration.