Why is my iPhone storage space not adding up?

My iPhone 5s iOS 9.2 62gb is saying that I only have a few gbs of space but when I add everything up(photos, apps,.) it only adds up to 14gb.

IOS 9 also requires memory. So do all your emails, messages, documents, and open apps.

Might be a firmware glitch. Back up and do a factory reset and then restore. Hopefully, you'll have the right space then.

That means your phone need to clear up what you don't need