Blob.size

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

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

output {
  display: block;
  margin-top: 16px;
}

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

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