A geotagged photo often carries a second clock reading next to its coordinates: GPSTimeStamp (0x0007) and GPSDateStamp (0x001D), the UTC time at which the GPS position was obtained. In a typical EXIF block they are the only date and time with a known zone, which makes them the best reference for checking a camera clock.
The time is three unsigned rationals (hours, minutes, seconds) and the date an 11-byte string, YYYY:MM:DD plus a null. ExifTool's verbose mode shows the encoding, and its composite GPSDateTime joins the two with a Z for UTC:
GPSTimeStamp = 16 41 58 (16/1 41/1 58/1)
GPSDateStamp = 2026:05:14
[Composite] GPSDateTime : 2026:05:14 16:41:58ZFix time, not shutter time
The stamp belongs to the location fix. A phone reusing its last known position can stamp a time seconds or minutes older than DateTimeOriginal, and a camera that gets its position from a paired phone app can lag further. For working out a missing time zone offset that lag is harmless, because you round to the nearest 15 minutes anyway. For exact capture time it makes the GPS stamp a poor source.
Some older files carry GPSTimeStamp without GPSDateStamp. Around midnight UTC that leaves the day ambiguous, so don't assume the date matches DateTimeOriginal.
Editing or removing it with ExifTool
These two tags are outside our whitelist: the reader doesn't show them and the editor can't change them. ExifTool can:
exiftool -GPSDateStamp -GPSTimeStamp -GPSDateTime photo.jpg
exiftool -GPSDateStamp="2026:05:14" -GPSTimeStamp="16:41:58" photo.jpg
exiftool -GPSTimeStamp= -GPSDateStamp= photo.jpgIf you hand ExifTool a time with a zone, it converts before writing: -GPSTimeStamp="18:41:58+02:00" stores 16:41:58.
One privacy gotcha: clearing the coordinates in an editor, ours included, leaves these two tags behind, so the file still says when you were somewhere, just not where. The metadata remover deletes the whole GPS IFD along with everything else. In a JPEG that IFD sits inside the APP1 EXIF segment. Other ways to drop location, including on phones, are in the location removal guide.