Manatee

Why photos get bigger when you export them from Photos on a Mac

· 6 min read

When photos exported from the Photos app come out much larger than the originals, the export settings are almost always the reason. Your iPhone most likely saved them as HEIC, a compact format, and the export turned them into JPEG at Maximum quality and Full Size, or into TIFF or PNG, which are far larger still. Export as JPEG at High quality and a sensible size, keep them as HEIC with Export Unmodified Original, or shrink files you have already exported.

Where the extra size comes from

Several settings stack up, and each one adds size on its own.

  • HEIC to JPEG. If your iPhone’s Settings, Camera, Formats is set to High Efficiency, it saves photos as HEIC. HEIC is a newer, more efficient format, so the same picture as a JPEG needs noticeably more space.
  • Maximum quality. Photos offers Low, Medium, High and Maximum for JPEG. Maximum keeps detail that is very hard to see and costs a lot of space for it.
  • Full Size. Recent iPhones can take photos at very high resolutions. Full Size exports every pixel, even if the picture will only ever be seen on a phone screen.
  • TIFF and PNG. Both are lossless formats. They suit graphics, scans and files headed for further editing, but a photo saved in either is many times the size of a JPEG. TIFF with the 16-bit option on is larger again.
  • Edits. An edited photo cannot be exported in its original compressed form. Photos renders the edited version fresh, in whichever format you pick.

The same thing happens with video, for similar reasons; why a video got bigger after you converted it covers that side.

Check what you are comparing

Before changing anything, confirm where the size is going.

  1. In Photos, select a photo and choose Window, Info (or press Command-I). The Info window shows its format, dimensions and file size.
  2. Export the same photo, then select the exported file in Finder and press Command-I.

If the original says HEIF and the export is a JPEG several times larger, the format and quality settings are the cause. If the export is a TIFF or PNG, the format alone explains it.

Export at a sensible size

For photos you are sending, posting or uploading, JPEG at High quality is the practical default.

  1. Select the photos in Photos.
  2. Choose File, Export, Export Photos. The menu item names how many photos you selected.
  3. Set Photo Kind to JPEG.
  4. Set JPEG Quality to High. Keep Maximum for photos that will be printed large or edited further.
  5. Set Size to Large for general sharing. Choose Custom to set a maximum width or height, such as 2048 pixels, for email or the web. Keep Full Size for prints.
  6. Decide on Location Information. If it is checked, the exported files carry the place each photo was taken. Uncheck it for anything public; how to remove GPS location from photos covers the rest.
  7. Click Export and choose a folder.

If you need a specific ceiling, such as an upload form that caps photos at a few hundred kilobytes, how to get a photo under 200 KB walks through hitting an exact target.

Keep HEIC when the photos stay on Apple devices

If the photos are going to another Mac, an iPhone or iPad, or your own backup, HEIC is the smaller option and nothing needs converting.

Choose File, Export, Export Unmodified Original. You get each photo exactly as the camera saved it, usually as HEIC. Two things to know: any edits you made in Photos are left behind, and a Live Photo comes out as two files, the still and a short video.

If you want your edits and a compact file, export as JPEG first, then convert those JPEGs to HEIC. That is a second round of lossy compression, though at sensible settings it is very hard to see. How to convert photos to HEIC to save space covers that route, and HEIC explained covers who can and cannot open the result.

Shrink photos you have already exported

If a folder of oversized exports already exists, you do not need to go back to Photos.

Preview, for a few files: open the photo, choose File, Export, pick JPEG or HEIC, and move the Quality slider. Preview shows the resulting file size as you adjust it. To reduce the pixel dimensions as well, use Tools, Adjust Size before exporting.

Terminal, for a whole folder: sips ships with macOS and can convert and resize in one pass. This makes JPEGs at quality 80, no larger than 2048 pixels on the long side, in a new folder:

mkdir ~/Desktop/Smaller
sips -s format jpeg -s formatOptions 80 -Z 2048 ~/Desktop/Export/* --out ~/Desktop/Smaller

Use -s format heic instead to make HEIC files. The originals in the Export folder are left as they are.

Manatee, for a batch without Terminal: open it, choose Convert, drop in the exported TIFFs, PNGs or JPEGs (or a whole folder), and choose JPEG or HEIC. Each converted copy is written next to its original, which is never modified, and everything runs on your Mac with nothing uploaded. It is free for 24 hours with every feature, then $9 once. If the photos are going out into the world, Manatee’s Clean mode strips GPS and camera details from the copies as well.

Questions

Is High quality visibly worse than Maximum? On a screen, rarely. The difference shows mainly in large prints and in heavy editing afterward. Export a test photo both ways, open them side by side, and compare the sizes in Finder.

Why is a PNG export so much bigger than the JPEG? PNG stores every pixel exactly, which suits screenshots and graphics with flat color. A photo has fine detail everywhere, so a lossless format has to keep all of it. Lossy versus lossless explains the trade.

Will exporting at a smaller size change the photos in my library? No. Exporting always makes new files. The photos in your library stay exactly as they were.