How storage is calculated:
To calculate the storage for accounts we add your original size image uploads (Plus and Free accounts both have original size images stored), and the size of any videos you have uploaded to your account.
If you do not wish for your original size images to be stored, please resize your photos before uploading them to your Photobucket account. That will ensure that your storage limit remains low, due to the smaller file sizes.
Storage limits for Free and Pro accounts:
Free accounts are given 2GBs of storage (Plus any additional storage you carried over from the old site). If you require more storage (your account is full) than that, you can upgrade to any of the Plus tiers available. You can read all about what each of those offer here.
Album storage limits:
There is a 2500 image limit for albums. If you are seeing messaging stating "album size limit exceeded", that album is full, and you will need to create a new album to upload future images to.
There is a 200 sub-album limit for every parent-album. All user-created albums will fall under your Your Bucket, or your default album. You can have 200 sub-albums under Your Bucket, and each of those albums can have 200 sub-albums.
You can view the amount of storage used at any time by going to the Account tab in your Settings: Click Here (must be logged in to Photobucket)
The image below is information available on the middle of that page.