How to change the date a photo says it was taken

Photo libraries sort by the date taken, which is the EXIF field DateTimeOriginal inside the JPEG, written by the camera from its own clock. It is not the file’s "created" or "modified" date, which belong to the disk and change whenever the file is copied. Change DateTimeOriginal (and, to be tidy, the two related fields) and every program that reads EXIF will show the new date. Windows Explorer can do it for one photo or several; ExifTool shifts a whole folder by an amount; RETAG does it for one JPEG in the browser tab without re-saving the picture.

The dates a photo carries

The EXIF dates are plain text in the form 2024:07:14 18:32:05, with colons in the date as well as the time, and no time zone. That is why a photo from a trip can appear hours out of order among photos from a phone: the camera recorded local time with no zone, and the phone recorded the zone as well. The time zone fields were added in EXIF 2.31, in 2016, to fix exactly this.

One photo, or a few, on Windows

Right-click the JPEG, Properties → Details, click the value beside Date taken, and type the new date and time. Select several photos first and the change applies to all of them, setting each to the same date. It is offered for JPEG, but not for every format.

On a Mac, Photos has Image → Adjust Date and Time, which changes the date in the Photos library. Check an exported copy if the date needs to travel with the file to somebody else.

A whole folder an hour out

The commonest case is a camera clock that was wrong for a whole trip, where every photo needs the same shift rather than the same date. That is a job for ExifTool, free and the reference tool for photo metadata. exiftool "-AllDates+=1" folder moves the date taken, the digitised date and the modified date of every photo in the folder one hour later; -= moves them earlier, and a value such as 0:0:1 2:30:0 shifts by one day, two hours and thirty minutes. It keeps an _original copy of each file unless told not to.

To find the shift, photograph a clock with the camera, or find one photo whose real time you know, and subtract.

One photo in the browser

RETAG opens a JPEG in the tab and shows what it says: the three dates, the time zone, the location, the orientation, the camera and the credits. Type the date taken, tick the box to set the digitised and modified dates to match, and add a time zone if you know it. Only the EXIF block is rewritten; the compressed picture is copied across byte for byte, so nothing is lost to re-saving, and the photo is not sent anywhere.

Three limits, which the page also states. It edits one JPEG at a time, so a folder with a clock error belongs to ExifTool. It rewrites EXIF and leaves an XMP copy of the date, if the file has one, as it was; a program that reads the XMP copy first may keep showing the old date. And a camera maker’s note is carried across as a block of bytes, so on some cameras the maker’s own software may no longer show lens or focus details afterwards.

Opening a photo and checking its dates is free. Saving the changed photo is part of OBSCURA Pro, or US$1 to save from one tool for a day.

A word on what a date proves

Because the date taken is a line of text anyone can change, it is evidence of nothing on its own. If a photo’s date matters to somebody else, such as an insurer, a court or a landlord, say that you corrected it and why. How to tell if a photo has been edited covers what does and does not survive this kind of change.