Quickly find the current used storage of your site collection by using REST

If you want to find out how much storage your SharePoint site collection is currently using then you can use the following REST url in your browser

://<Replace your Site Collection Url>/_api/site/Usage/Storage

http://sp/_api/site/Usage/Storage

You will get response similar to following. Please note SharePoint report storage in bytes so to get the size in MB you need to divide it by 1048576 .

In following example: storage in MB will be 8038715 / 1048576 = 7.67 MB