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

  keys,                      // null, string, or array of strings
  function(bytesUsed){...}   // function

This API is also available as<storagetype>.getBytesInUse() in a version that returns a promise.

<storageType> will be one of the writable storage types — storage.sync or storage.local.


A key (string) or keys (an array of strings) to identify the item(s) whose storage space you want to retrieve. If an empty string or array is passed in, 0 will be returned. If you pass null here, the function will return the space used by the entire storage area.
callback Optional
A callback function that is run when the operation completes. If the operation is successful, the function is passed an integer, bytesUsed, representing the storage space used by the objects that were specified in keys. If the operation fails, runtime.lastError is set.

Browser compatibility

Chrome Edge Firefox Firefox for Android Opera
Basic support Yes Yes No No 33


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.

Document Tags and Contributors

 Contributors to this page: Makyen, chrisdavidmills, wbamberg
 Last updated by: Makyen,