The Blob.size property returns the size in bytes of the Blob or a File.


var sizeInBytes = blob.size


A number.


// fileInput is a HTMLInputElement: <input type="file" multiple id="myfileinput">
var fileInput = document.getElementById("myfileinput");

// files is a FileList object (simliar to NodeList)
var files = fileInput.files;

for (var i = 0; i < files.length; i++) {
  console.log(files[i].name + " has a size of " + files[i].size + " Bytes");


Specification Status Comment
File API
The definition of 'size' in that specification.
Working Draft Initial definition.

Browser compatibility

Feature Chrome Edge Firefox (Gecko) Internet Explorer Opera Safari (WebKit)
File.size 5 (Yes) 4.0 (2) 10.0 11.10 5.1
Feature Android Edge Firefox Mobile (Gecko) IE Phone Opera Mobile Safari Mobile
File.size No support (Yes) No support No support No support No support

See also

Document Tags and Contributors

 Contributors to this page: erikadoyle, vinnymac, Nickolay, fscholz, Jeremie, Cobra, Sheppy, ethertank, ziyunfei, Crash
 Last updated by: erikadoyle,