Batch Resize Images on Mac with Preview
You can easily batch resize groups of images within Mac OS X by using the included Preview app, that is, taking a group of pictures set at one or various resolutions, and collectively resize them all together in a group to a new resolution, outputting either as the same file or as a new file saved at the newly desired resolution. Long ago you had to buy expensive third party software for this purpose, but no longer is there a need for any additional downloads or expensive photo editing applications to perform these tasks on a Mac. Instead you only need Preview, which is free with every Mac and every version of Mac OS X!
Here is how to use Previews’ powerful yet easy batch image resize feature to change the resolution of multiple files in one fell swoop, all in a few simple steps.
How to Batch Resize Images in Mac OS X
You will need to launch Preview, which is in the /Applications/ folder, to get started. Preview is also usually the default image editor and can be typically opened by just opening any picture. Once Preview is open, proceed with the following simple directions:
- Select all the images you want resized in the Finder, and then open them within the Preview app
- From Preview, select all of the images that you want to batch resize from the left-side thumbnail drawer (Command+A will select them all)
- Now, go to the menu labeled “Tools”, and then choose “Adjust Size”
- Enter a value for what you want the new width and height to be
- Next, navigate to the ‘File’ menu and click “Save All” or, to save a NEW version that is resized, choose “Export Selected Images…” or “Save As”
If you “Save All”, all the images will instantly save resized over the existing versions. If you “Export” or “Save As”, you’ll create newly resized images in addition to the existing photos.
Choose a path to save the files in the Save dialog to if you’re exporting or using “Save As” features, then just wait for all of the images to finish resizing to their new resolutions. The batch resizing takes place fairly quick, but the precise speed is dependent on your available system resources and speed of the Mac.
This works in Preview that is included in virtually all versions of Mac OS X, learn it once and you’ll have the ability to resize large groups of photos and picture files easily in a batch process that is extremely easy.
The video tutorial below walks through the step-by-step process of using Preview to resize multiple images as opened from the Mac file system, as you’ll see it’s a piece of cake:
Updated: 5/14/2019 for clarification. Note the precise menu language varies slightly per version of Mac OS or Mac OS X, as older versions differ from the most modern incarnations of Mac OS X. Nonetheless, the procedure works in all Preview versions, whether it’s in MacOS Mojave, MacOS High Sierra, Sierra, Snow Leopard, OS X Lion, OS X Mountain Lion, OS X Mavericks, OS X Yosemite, El Capitan, and likely every version where Preview remains as a staple of the operating system.
Advice worked perfectly with High Sierra 10.15 to resize and upload 530 pictures and videos to dropbox. Very useful tip!
i batch rotate but the file size is not the same as the original, it smaller like 6MB to 3MB
Thanks a lot for this!! works great on Mountain Lion (10.8.2.)
I loved Preview for reducing batches of photos then either drag and drop or file insert photo into Word. Preview does reduce the file size and dims, but when I drag/drop or insert the photo into word. The image reverts back to original size. Used to work great in Lion. but not so in El Capitan. any suggestions?
Thank you so much, you helped me big deal. Everything is soooo easy when you know how to do it… :D
Just wanted to say that this still works great and no expensive clunky graphics editing software required.
Preview is the bomb!
Oh good lord – Never do anything to any type of “original” file. Make a copy and try that first. I have about 1500 photos I decided to try this with. I made a new directory (actually 2 – an “input” and an “output”) on my desktop. I *COPIED* files to the Input folder/directory. I tried this on thoe files and output to the “Output” folder/directory. Worked flawlessly – OS X 10.10.5
I tried this, and yes it allowed me to resize the images – but Finder isn’t refreshing the fie size for some reason…
Thanks for this! Did my job really fast. Haha!
Gosh, I was looking for that solution for a long time! Thank you very much.
This does not work AT ALL on Yosemite. The resize function of preview no longer works on any of my images.
It’s funny seeing the comments here. In Mountain Lion it barely works. In Yosemite it doesn’t work at all. Maybe with the next “upgrade” preview won’t even open images.
Macs are steadily becoming crappier and crappier.
I resize images every day in OS X Yosemite with Preview, what do you mean this doesn’t work? Go to the Tools menu > Resize
its not a highlighted option anymore,
Same for me: OS X 10.10.1:
1st annoyance: “Save All” menue item has been removed sometimes back; obviously the developers think you don’t need this crucial feature; also did not find any magic easter egg to maybe get back this menue item, by pressing 5 other keys at the same time…
2nd annoyance: resizing more then arond 10 items crashes preview – always and any time!
3rd annoyance: No, using Automator for such a trivial task is NOT an option!
So actually: preview gets worse and crappier with any new OS X generation.
Since the developers decided that a red markup colour is not what you need to highlight text in pdf-files, but pink is the future, i switched to ADOBE ACROBAT.
Now i need again to look for another tool, that allows me to work with my mac, just for resizing pictures. For sure Appstore provides me with an commercial app for this…
APPLE, please LISTEN: this sucks enormously, i need to work with my Mac – seriously! Learn from other operating systems, where users at least have CHOICES!
My impression is that this device gets more and more useless
this is really stupid to give a tip like this without a big fat warning what preview is really doing under SL and later…
IT INSTANTLY ALTERS THE ORIGINAL FILE ON DISK!!!
if it crashes theres no way to get the original back!
it only reverts back to original if you close and choose this option, else the change is permanent!
lost a ton of unrestorable originaly this way, YEAH THANX FOR THAT!!!
stop giving tips if you dont consider all the obvious dangers and warn people about them!
Be warned. This does not work properly on Mountain Lion, and you need a ton of space on your startup disk. I tried to resize a 1000 photos (time-lapse) on an external drive, and it did not worked. I could not save nor cancel the operation. I was trying to make a smaller copy, but most files were written over, and I cant get the original files back! Later I tried this on my internal drive, but it failed again (Samsung SSD). I’ve lost my original files in the process, which is the worst that could happen. Be very very careful!
[…] you can also create a simple ‘Batch Resize’ Service with Automator, or just do a manual bulk resizing process on a group of pictures using Preview app, which also comes with every version of Mac OS […]
Useless! there no SAVE ALL!! in Lion.
Works perfectly – I reduced 137Mb of photos to just 8.8Mb in about 1 minute! Quality was still fine for use in docs.
NB: this process replaces the existing file so make sure you have a copy if you still want to keep the original!
This just got me into big trouble.
I tried to batch process 300 photos in preview and it proceeded to open every one of them, freezing my mac.
I had to force quit. Now, however, anytime I open Preview, it commences with the process of opening all 300 pics again.
I’ve no idea what to do.
When I had a PC, I had a little program that just resized and put them all in a folder rather than opening up every picture.
in case anyone has the same problem when opening again:
hold SHIFT when clicking preview will erase the previous file list and open it blank!
Hi I am wondering if I resize will I have copies of the originals?
No – you won’t. this process replaces the existing file so make sure you have a copy if you still want to keep the original!
[…] like the iPhone screen, so you may want to save them all in a folder then take a moment to batch resize them using Preview to a resolutio that is appropriate for your needs. Ok enough chat, let’s get to […]
[…] Depending on the amount of images selected to convert, their resolutions – which can also be resized at the same time if desired, and their file formats, this process can either be very fast or somewhat time […]
We’re is “SAVE ALL”?!
OS X Mountain Lion.
Thank you. I also noticed that you can undo (command+z) if you want to revert back to the original file.
[…] most Mac users will likely prefer to use Preview to batch resize images because of the ease of use, advanced users often like to go with the command line for repetitive […]
This is a good solution for a few dozen images but you can’t open a few hundred images and then perform the batch.
Searching for batch, I was thinking hundreds of images, this process is geared more towards a dozen or so.
If knowing this gets you closer to dropping Photoshop, you don’t know Photoshop.
Thanks!!!! You saved my life!!!
Ever since I upgraded to Lion, Preview will crash when I do batch resizes of 10 pictures or more. The more pictures I try to batch resize, the harder time it has. Both on my MBA 13 with SSD and 27″ iMac w/ SSD.
Quicklook and preview in Lion suck. Quicklook fails to launch after tens of shifts among a bunch of figures, no matter what format they are. Preview crashes if more than tens of figures are opened at the same time. Never work properly.
If you select all pictures and click save preview will crash, what you do is to select batch of ten (inside preview after resizing all pictures) and then click save then the next 10 and click save … etc etc… this way preview wont crash
Very much appreciated – you’ve saved me a lot of time!
[…] powerful app that is often underutilized for batch photo processing tasks, I use it frequently to batch resize images for wallpaper posts and other purposes, it’s quick, lightweight, and much less demanding on […]
Excellent thank you!!!!!
[…] to resize a ton of pictures? Instead of downloading a third party application or using Preview, you can use Automator to handle the entire operation, even renaming the images to indicate they […]
GRACIASSS!! Terima kasih.
Be careful when you use this tip which can be useful, you’ll lose the original sized picture… There is no choice for the saving name or place.
You don’t have to overwrite the original image. If you choose ‘Export’ you can choose where to save the image. (Lion)
Actually, the first time I did this with a batch on Mt Lion, it didn’t alter the originals. Suddenly on the second batch, it started to AUTOMAGICALLY saving the adjustments to the originals. So the best approach would be to copy the images to a NEW folder, and make the changes appropriately. I believe the problem is in fact a bug with Preview, and not the intended way to behave.
now THIS is cool, I hate launching into bloatware Photoshop just to batch resize pictures and I had no idea Preview was so capable. If Apple adds a few more features to Preview there will be little reason to use Photoshop at all…
Not sure this is an informed opinion.
If you are using SL you have to go to Preview/Preferences/General –> “open all files in one window”