Payload Size Analyzer

Measure UTF-8 bytes, JSON minification savings, character counts, and estimated transfer volume locally in your browser.

Payload text stays in this browser

Payload input

Measure the body

Paste a request or response body. The analyzer measures the text exactly as entered, including whitespace and UTF-8 multibyte characters.

Payload type Expected requests (optional) Request volume period

Payload body

Body-size summary

Results

Ready to analyze

Use the sample or paste the payload you want to measure.

Exact UTF-8 bytes 0 Body only, before HTTP framing or compression

Decimal size0 B

Binary size0 B

Characters (code points)0

Lines0

Detected typeNot measured

Minified JSON bytesUnavailable

Whitespace savingsUnavailable

Transfer for selected periodAdd request volume

Approximate 30-day transferAdd request volume

Transfer estimates multiply uncompressed body bytes by the request count. They exclude headers, protocol framing, TLS, retries, provider envelopes, and response data.

Read the number correctly

Characters and transfer bytes are not interchangeable.

UTF-8 uses one byte for many common ASCII characters and multiple bytes for many other characters. That is why the analyzer encodes the actual text instead of using a JavaScript string length as a byte count.

1
Measure UTF-8 bytes
The exact body-size result comes from the browser's UTF-8 encoder and includes every space and line break.
2
Keep units explicit
Decimal KB uses 1,000 bytes. Binary KiB uses 1,024 bytes. Both are shown so the label never hides the conversion.
3
Minify without changing values
For valid JSON, formatting and minification preserve the original string, number, and escape spellings. Only insignificant whitespace changes.
4
Separate size from compression
Minification removes JSON whitespace. Network compression can reduce transfer size further, but its result depends on content and configuration.

Planning estimate: This tool measures a body string, not a captured network exchange. Confirm production transfer sizes with your own client, server, compression settings, protocol, and representative payloads. Learn when and how an API response can be cached safely. Compare gzip and Brotli on three reproducible fixtures.