Storage usage option helps you track the amount of storage space used by a form. For your Zoho Forms account, your allocated storage will vary depending on your plan. The storage usage option will give the storage statistics of each form which includes the space used by upload fields and form attachments. 

To learn about a form's storage usage,

1. Under My Forms, hover over the horizontal ellipsis of the desired form.
   
2. Select Storage Usage from the drop-down as shown below.
   
   
   
   The storage usage details will be displayed in a pop-up.