Gets the amount of storage space, in bytes, used one or more items being stored in the storage area.

This function only exists in
It does not exist in

This is an asynchronous function that returns a Promise.


var gettingSpace =<storageType>.getBytesInUse(
  keys                      // null, string, or array of strings

<storageType> can only be storage.sync, not storage.local because of this bug.


A key (string) or keys (an array of strings) to identify the item(s) whose storage space you want to retrieve. If an array is passed in, 0 will be returned. If you pass null or undefined here, the function will return the space used by the entire storage area.

Return value

A Promise that will be fulfilled with an integer, bytesUsed, representing the storage space used by the objects that were specified in keys. If the operation failed, the promise will be rejected with an error message.

Browser compatibility

Update compatibility data on GitHub
ChromeEdgeFirefoxOperaSafariFirefox for Android
getBytesInUseChrome Full support YesEdge Full support 14Firefox Full support 78
Full support 78
Notes Only supported by the sync storage area.
Opera Full support 33Safari Full support 14Firefox Android No support No


Full support  
Full support
No support  
No support
See implementation notes.
See implementation notes.

This API is based on Chromium's API. This documentation is derived from storage.json in the Chromium code.

Microsoft Edge compatibility data is supplied by Microsoft Corporation and is included here under the Creative Commons Attribution 3.0 United States License.