Staaarter Tools

Top Letter Finder

Reports the N most frequent letters in your text (case-insensitive) as a ranked list with their counts, useful for letter-frequency analysis, cryptography puzzles, and word games. A free online tool from Staaarter, right in your browser.

Runs locallyUpdated 2026-07-23
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Overview

Introduction

Which letters show up most often in a piece of text comes up in cryptography puzzles, word games, and basic frequency analysis, and counting by eye doesn't scale past a sentence or two.

This tool ranks letter frequency for you instantly, and it runs entirely client-side, so nothing you paste is ever uploaded to a server.

What Is Top Letter Finder?

A frequency finder that reports the N most common letters in your text, case-insensitive, as a ranked plain-text list with counts.

It runs entirely client-side as part of this site's String Tools collection, so nothing you paste is ever uploaded to a server.

How Top Letter Finder Works

The text is lowercased and every alphabetic character is tallied into a frequency map, the map is sorted by count (highest first, ties broken alphabetically), and the top N entries are formatted as a ranked list.

The transformation happens synchronously in JavaScript the moment you type or change N, with no network round trip involved.

When To Use Top Letter Finder

Use it for classic-cipher frequency analysis, checking letter distribution in generated text, or settling word-game arguments about which letters are most common.

It's a fast way to get the answer without opening a spreadsheet or writing a one-off script just to check.

Often used alongside Top Word Finder, Letter Sum Calculator and Text Entropy Calculator.

Features

Advantages

  • Case-insensitive counting avoids splitting 'A' and 'a' into separate entries.
  • Configurable N lets you see as few or as many top letters as you need.
  • Breaks ties alphabetically rather than arbitrarily, so the ranking is stable and two runs over the same text always agree.

Limitations

  • Only counts the basic Latin alphabet (a-z); accented and non-Latin letters aren't tallied.
  • Reports raw counts rather than percentages, so distributions taken from texts of different lengths cannot be compared directly.

Examples

Finding the top 3 letters

Input

mississippi

Output

1. i — 4
2. s — 4
3. p — 2

'i' and 's' tie at 4 occurrences each and are broken alphabetically; 'p' follows with 2.

Best Practices & Notes

Best Practices

  • Increase N when comparing letter distribution across a longer piece of text, since the top 5 alone may not capture meaningful differences.
  • Use a longer sample when comparing against standard English letter frequencies, since short text is dominated by whichever words happen to appear in it.
  • Divide each count by the total letters yourself when comparing two texts, because raw counts scale with length.

Developer Notes

Letters are extracted with `input.toLowerCase().match(/[a-z]/g)`, tallied in a `Map<string, number>`, then sorted with `.sort((a, b) => b[1] - a[1] || a[0].localeCompare(b[0]))` before slicing to the requested N.

Top Letter Finder Use Cases

  • Classic substitution-cipher frequency analysis
  • Checking letter distribution in generated or sample text
  • Word-game and puzzle research into common letters

Common Mistakes

  • Expecting spaces or punctuation to appear in the ranking; only alphabetic characters are counted.
  • Drawing conclusions from a short sample, where a single repeated word can push an otherwise rare letter to the top of the ranking.

Tips

  • Pair this with the Text Entropy Calculator to see both which letters dominate and how predictable the text is overall.
  • In ordinary English 'e' and 't' usually lead, so a ranking that departs sharply from that is often the first clue that text has been enciphered.

References

Frequently Asked Questions