What gets removed and what survives
Removal works on the groups you see in the viewer. Everything in a group goes when that group is selected, in every place the data can sit. A GPS position, for example, can be in EXIF, in XMP, in IPTC place fields, in Photoshop data, in the small thumbnail inside the file and in a second picture stored after the first, and Remove location only clears all of them. Data that cannot be read in detail (an attached video, an unknown segment) is searched for signs of a position, and goes with the location when one is found.
- Gone with Remove everything: location, camera and lens details and serial numbers, dates and time zones, exposure settings, author, copyright, captions and comments, thumbnails, XMP including editing history, IPTC, maker notes, other extra segments, and data after the end of the picture such as the video of a motion photo.
- Stays by default: the colour profile, and for a sideways photo a tiny EXIF block holding only the rotation. The file header the picture needs (its size, colour layout and compressed data) always stays, as do the colour and animation parts of PNG and WebP.
- Stays unless you remove it: in Remove location only, the maker note stays, because it cannot be read well enough to edit. An attached video stays too, unless it has a location of its own.
The size you save is usually a few kilobytes. It is more when a file carries a big thumbnail, a long XMP editing history or an attached video, which can be megabytes. The point is privacy, not file size.
Apps that already remove metadata, and ones that do not
Some messaging apps, social networks and websites remove location data when you upload a photo, and some keep it, or pass it on when you send the original file or a full quality version. The behaviour differs between services, can depend on a setting, and can change with an update. You cannot see what happens on their servers, and the person who receives the file may get a different copy from the one that is shown to the public.
Cleaning the file before you share it does not depend on any of that. It also covers the places where a copy ends up that you do not control: an email attachment, a cloud folder, a classifieds site, a forum.
Screenshots versus photos
A photo from a camera or phone usually carries the most: position (if location was allowed), device, lens, settings and a thumbnail. A screenshot has no GPS position and no camera, so it carries far less. Even so, a screenshot tool can write the program name or a date, and a PNG can hold text notes. A photo of a screen, a printed page or a whiteboard is an ordinary photo and carries ordinary metadata. Drop the file into the viewer if you want to know what yours holds.
What removal cannot hide
- The picture itself. A street sign, a house number, a recognisable skyline, a face or a reflection can identify a place or a person without any metadata. Crop or blur it yourself.
- The file name. A cleaned file keeps the base name of the original with -clean added and the extension of its format (a HEIC saved as a clean JPG ends in -clean.jpg). A file that is left as it was keeps its name. If the name has a place, a person or a date in it, rename the file.
- Dates outside the file. Your computer stores created and modified dates for the file itself. They are not part of the file's contents and are not changed here.
- Other copies. Removal changes the copy you download. Copies already sent or uploaded keep what they had.