Why is my photo storage still using up memory when I have deleted photos from phone?

[iMore Question]

Most of my storage is used up on photos and can't work out why

 

[Rob Phillips]

Welcome to iMore! Individual photos don't actually use up that much storage but collectively they can eat up space. How many photos did you delete?
You can save some local storage by using iCloud Photo Library. Go to Settings > iCloud > Photos, and toggle on iCloud Photo Library. Make sure you have "Optimize iPhone Storage" selected. Keep in mind it takes time to upload your photos and optimize them locally on your device so you may not notice an immediate difference.
Another option is to use a cloud backup service like Dropbox, OneDrive, or Amazon Photos. Once your photos are uploaded you can delete them from your device. If you're an Amazon Prime member you can upload an unlimited amount of photos.