What does this tool measure?
This calculator reports the true byte size of your JSON (as it would be sent over the network), its character and line count, and how much smaller it would be once minified — all computed instantly in your browser.
How to use this tool
- Paste your JSON into the left-hand box.
- Click Calculate Size.
- Review the byte size, character/line counts, and minified size comparison.
Frequently asked questions
How is byte size different from character count?
For plain ASCII text they're usually the same, but any multi-byte Unicode characters (like emoji or non-Latin scripts) take up more bytes than a single character, which this tool accounts for using the JSON's UTF-8 byte size.
Why does minified size matter?
Whitespace used for readability adds extra bytes with no functional value. Knowing the minified size tells you the real payload cost once whitespace is stripped for production use, like an API response.
Does this tool upload my JSON anywhere?
No — all size calculations happen locally in your browser. Your JSON never leaves your device.