String Byte Length Calculator
Calculate the byte length of any string in UTF-8 encoding. Free, instant.
How to use this tool
- Enter text in the fields above.
- Results update instantly as you type — or click Calculate.
- Read your utf-8 byte length and the full breakdown beneath it.
Strings in JavaScript are UTF-16, but network transmission and storage often use UTF-8. This tool calculates how many bytes your text occupies in UTF-8.
Frequently asked questions
- Why does byte length differ from character count?
- Non-ASCII characters (like accented letters or emoji) take 2-4 bytes in UTF-8, making the byte length larger than the character count.