W3cubDocs

/Web APIs

Blob: size property

The Blob interface's size property 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

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

	Desktop						Mobile
	Chrome	Edge	Firefox	Internet Explorer	Opera	Safari	WebView Android	Chrome Android	Firefox for Android	Opera Android	Safari on IOS	Samsung Internet
`size`	5	12	4	10	11	6	4.4	18	4	11	6	1.0