StorageManager: estimate() method

Baseline 2023

Newly available

Since September 2023, this feature works across the latest devices and browser versions. This feature might not work in older devices or browsers.

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

Note: This feature is available in Web Workers.

The estimate() method of the StorageManager interface asks the Storage Manager for how much storage the current origin takes up (usage), and how much space is available (quota).

This method operates asynchronously, so it returns a Promise which resolves once the information is available. The promise's fulfillment handler is called with an object containing the usage and quota data.

Syntax

estimate()

Parameters

None.

Return value

A Promise that resolves to an object with the following properties:

quota: 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: 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 Non-standard: An object containing a breakdown of usage by storage system. All included properties will have a usage greater than 0 and any storage system with 0 usage will be excluded from the object.

Note: The returned values are not exact: between compression, deduplication, and obfuscation for security reasons, they will be imprecise.

You may find that the quota varies from origin to origin. This variance is based on factors such as:

How often the user visits
Public site popularity data
User engagement signals like bookmarking, adding to homescreen, or accepting push notifications

Exceptions

TypeError: Thrown if obtaining a local storage shelf failed. For example, if the current origin is an opaque origin or if the user has disabled storage.

Examples

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

HTML

html

<label>
  You're currently using about <output id="percent"> </output>% of your
  estimated storage quota (<output id="quota"></output>).
</label>

JavaScript

navigator.storage.estimate().then((estimate) => {
  document.getElementById("percent").value = (
    (estimate.usage / estimate.quota) *
    100
  ).toFixed(2);
  document.getElementById("quota").value =
    `${(estimate.quota / 1024 / 1024).toFixed(2)}MB`;
});

Result

Specifications

Specification
Storage # ref-for-dom-storagemanager-estimate