Mac storage basics · Creative and media apps
Does editing photos in the Photos app use more space?
Short answer: A little — Photos keeps the original alongside each edit so you can revert. Export the edit and delete the original if you want one smaller file, at the cost of undo.
A little. Photos never overwrites your original: it keeps the original plus the edited version (and for videos, a rendered edit), so you can always choose Revert to Original. Heavily edited libraries are therefore somewhat bigger than the photos alone.
This is a safety feature, not waste. If you want a single smaller file, export the edited version and delete the original — but you lose the ability to undo the edits. See why the Photos library is bigger than your photos.