Blob: size property

Baseline Widely available

This feature is well established and works across many devices and browser versions. It’s been available across browsers since January 2020.

Note: This feature is available in Web Workers.

The size read-only property of the Blob interface returns the size of the Blob or File in bytes.

Value

The number of bytes of data contained within the Blob (or Blob-based object, such as a File).

Examples

This example uses an <input> element of type file to ask the user for a group of files, then iterates over those files outputting their names and lengths in bytes.

HTML

html
<input type="file" id="input" multiple />
<output id="output">Choose files…</output>

JavaScript

js
const input = document.getElementById("input");
const output = document.getElementById("output");

input.addEventListener("change", (event) => {
  output.innerText = "";

  for (const file of event.target.files) {
    output.innerText += `${file.name} has a size of ${file.size} bytes.\n`;
  }
});

Result

Specifications

Specification
File API
# dfn-size

Browser compatibility

Report problems with this compatibility data on GitHub
desktopmobileserver
Chrome
Edge
Firefox
Opera
Safari
Chrome Android
Firefox for Android
Opera Android
Safari on iOS
Samsung Internet
WebView Android
WebView on iOS
Deno
Node.js
size

Legend

Tip: you can click/tap on a cell for more information.

Full support
Full support
Has more compatibility info.

See also