Secure context
This feature is available only in secure contexts (HTTPS), in some or all supporting browsers.

The StorageEstimate dictionary's quota property is a conservative approximation of how much storage is allotted to the origin or Web app that called StorageManager.estimate(); there may be more space available, but there will not be less. This value is an estimate to help prevent its use for fingerprinting—that is, identifying a device using an amalgamation of the values of seemingly innocuous properties.


quota = StorageEstimate.quota;


A numeric value specifying an approximation of the total amount of storage space available for use by the application.


In this example, we obtain the usage estimates and present the percentage of storage capacity currently used to the user.

HTML content

  You’re currently using about <output id="percent">
  </output>% of your available storage.

JavaScript content {
  document.getElementById("percent").value =
      (estimate.usage / estimate.quota * 100).toFixed(2);



Specification Status Comment
The definition of 'quota' in that specification.
Living Standard Initial definition

Browser compatibility

Update compatibility data on GitHub
ChromeEdgeFirefoxInternet ExplorerOperaSafariAndroid webviewChrome for AndroidFirefox for AndroidOpera for AndroidSafari on iOSSamsung Internet
quotaChrome Full support 52Edge Full support ≤79Firefox Full support 51IE No support NoOpera Full support 42Safari ? WebView Android Full support 52Chrome Android Full support 52Firefox Android Full support 51Opera Android Full support 42Safari iOS ? Samsung Internet Android Full support 6.0


Full support  
Full support
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No support
Compatibility unknown  
Compatibility unknown

See also