How to Find Duplicate Letters in Text Online (2026)
Use our free Find Duplicate Letters tool to analyze any text and identify all letters that appear more than once. View results as a frequency table showing each letter, its count, and percentage. Duplicate letters are highlighted inline within the text for visual identification. Toggle case sensitivity and choose to exclude single-occurrence letters from the results.
How Duplicate Letter Detection Works
Duplicate letter detection scans every character in your text and counts how many times each letter (A-Z, a-z) appears. Letters that occur more than once are flagged as duplicates. The tool generates a frequency table sorted by count and highlights duplicate letters directly in the text preview. This is useful for word games, writing analysis, identifying pattern imbalances, and checking letter distribution in text.
How to Use Our Duplicate Letter Finder
- Paste or type text into the Find Duplicate Letters input area.
- Toggle case sensitivity if you want to treat “A” and “a” separately.
- Choose to exclude single-occurrence letters (show only actual duplicates).
- View the frequency table and inline highlights in real time.
- Copy the analysis or results to your clipboard.
Example Duplicate Letter Analysis
| Text | Duplicates | Frequency |
|---|---|---|
| hello | l, (h, e, o single) | l: 2 |
| mississippi | m, i, s, p | i: 4, s: 4, p: 2, m: 1 |
| aaa bbb ccc | a, b, c | a: 3, b: 3, c: 3 |
| abcdef | None | all letters appear once |
Common Use Cases
- Word games — identify the most and least common letters in puzzle answers and game text.
- Writing analysis — check letter repetition patterns in writing for stylistic analysis.
- Cryptogram solving — find the most frequent letters as a starting point for substitution ciphers.
- Typing practice — identify which letters you use most frequently for targeted typing drills.
FAQ
What counts as a duplicate letter?
A letter is considered a duplicate if it appears more than once in the text. Single-occurrence letters can be excluded from results using the toggle.
Does this include numbers and symbols?
No. Only letters (A-Z, a-z) are analyzed. Use the Character Frequency Counter for full character analysis including numbers and symbols.
Can I see the frequency of all letters including single-occurrence ones?
Yes. Disable “Exclude Single Occurrences” to see the full frequency table including every letter that appears in the text.
What does case-sensitive mode change?
When case-sensitive is on, “A” and “a” are counted as separate letters. When off, they are combined into a single count.
How are duplicate letters highlighted inline?
Duplicate letters are visually distinguished in the text preview — each letter that appears more than once receives a highlight color so you can spot them at a glance.
Try our free Find Duplicate Letters tool to identify repeated letters in any text with frequency tables and inline highlights.