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

The StorageEstimate dictionary is used by the StorageManager to provide estimates of the size of a site's or application's data store and how much of it is in use. The estimate() method returns an object that conforms to this dictionary when its Promise resolves.

These values are only estimates for several reasons, including both performance and preventing storage capacity data from being used for fingerprinting purposes. See the individual property pages for details.


quota Secure context

A numeric value in bytes which provides a conservative approximation of the total storage the user's device or computer has available for the site origin or Web app. It's possible that there's more than this amount of space available though you can't rely on that being the case.

usage Secure context

A numeric value in bytes approximating the amount of storage space currently being used by the site or Web app, out of the available space as indicated by quota. Unit is byte.

usageDetails Secure context

A dictionary containing a breakdown of usage by storage system. All included members will have a usage greater than 0 and any storage system with 0 usage will be excluded from the dictionary.


Storage Standard (Storage)
# dictdef-storageestimate

Browser compatibility

BCD tables only load in the browser

See also