How to shrink the file size of a PDF

Susan Snipes / Posted 6.21.2011

How to shrink the file size of a PDF

Are you a website content manager? Do you use PDFs for presentations or papers at your job? Occasionally, you'll have a PDF that's too big to upload to your website. Or you may have a larger PDF to send via email. Since you’re the kind of person who likes to be courteous to your colleagues, email recipients and website visitors, you naturally want to use the smallest possible PDFs that download as fast as possible. Fortunately for you, Acrobat has functions built in to reduce PDF file size. Here's how to shrink a PDF.

You'll need: Adobe Acrobat (not Acrobat Reader)

Part A: Basic method to reduce file size

1. OPEN: Open your PDF in Acrobat.
Go to Adobe Acrobat, and open your file. Make sure you have the file open in Adobe Acrobat, not Acrobat Reader or another computer-specific application such as “Preview” on the Mac.

2. REDUCE: Find the Reduce File Size command.
Go to “Document > Reduce File Size” in your Acrobat menu bar. This command is the same for both Windows and Mac OS versions of Adobe Acrobat.


3. COMPATIBILITY: Select a version of Acrobat.
Acrobat will now show you a Compatibility window. Select what version of Acrobat you'd like to save the file as.

4. SAVE FILE AS: Save the PDF with a new file name.
Acrobat will prompt you to save the file. Give your new file a name. Save the PDF in a location where you can find it.

5. PROCESS: Let Acrobat process the file.
Acrobat will do things like reduce the image sizes, remove unused elements and optimize the file for fast web viewing. Please be patient while this happens, as it may take several seconds or even a minute depending on how large your file is.

6. CHECK: See how small your PDF is now.
Check the file size and see how much Acrobat shrank your file. Hopefully you’ll be pleasantly surprised. If it’s not much smaller, you can move on to the Advanced Settings for fine-grained control and for maximum file shrinking!

Part B: Advanced settings to finely control file size optimization

If the basic file shrinking method above didn’t make your file size a lot smaller, don’t worry, you can use the Advanced Settings built into Acrobat to make your PDF super small!

1. OPEN: Open your PDF in Acrobat.
If your file is already open from Part A above, you’re set. Otherwise, open your PDF with Adobe Acrobat (not Acrobat Reader).

2. OPTIMIZE: Find the PDF Optimizer command.
Go to “Advanced > PDF Optimizer…” in your Acrobat menu bar.

3. OPTIMIZE: Update your optimization settings.
In the window that opens, you’ll be changing several settings as follows (or match them to the screen capture pictured below):

Check the “Images” checkbox on the left, and adjust the following settings:

  • For color images, downsample: Bicubic Downsampling to 100, compression JPEG, quality Medium
  • For grayscale images, downsample: Bicubic Downsampling to 100, compression JPG, quality Medium
  • For Monochrome images, downsample: Bicubic Downsampling to 150, JBIG2, quality Lossy

Check the “Discard Objects” checkbox on the left, and adjust the following settings:

  • Discard all alternate images.

Check the “Discard User Data” checkbox on the left, and adjust the following settings:

  • Check ALL boxes to discard all user data.

Check the “Clean Up” checkbox on the left, and adjust the following settings:

  • Object compression options set to: Compress entire file.

Check ALL boxes to clean up everything.

Note: Feel free to experiment with these settings on your own.

4. SAVE: OK to proceed.
Once you’ve adjusted all the settings above click the “OK” button. The PDF will now be saved with your new optimized settings. It will be saved in the same location and with the same name.

5. CHECK: See how small your PDF is now.
Check the file size and see how much Acrobat shrank your file. If you didn’t get a smaller file with part A, these advanced settings will do the trick. Happy file shrinking!

2 MB or less

A good rule of thumb for PDFs is to make them less than 2MB. Yes, it’s possible to use these steps to shrink PDFs that are 50+ MB with lots of high-resolution images down to 2 MB or less!

Think compatibility

Most computer users have Acrobat Reader, but they may not have the latest version. Consider saving your PDF’s compatibility to a previous version (such as Acrobat 7) so that all your recipients can open the file.

Save your settings

Once you have customized settings you like using the PDF Optimizer, you can save these selections as your own custom settings for your use in the future. Click the “Save” button at the top of the Optimizer screen and name the settings for future use.

Image Source: wmshc_kiwi

Susan Snipes

Susan Snipes

Owner and principal of Q Digital Studio

Susan Snipes is the owner and principal of Q Digital Studio. Friends of Susan used to call her Susie Q, Miss Q, or just Q. The nicknames may not have stuck, but that infamous letter Q became the namesake for Susan's dream: her own business. Now Miss Q is making a name for herself as a community-minded web entrepreneur and ExpressionEngine expert.

As a college student at Case Western Reserve University, Susan became interested in web design, and self-taught her way into a number of freelance gigs. She left Cleveland with a degree in Art History and Architecture, but found her true calling in web design and development. Susan worked in New Orleans before migrating west to Denver, a place she happily calls home with her husband Corey and dog, Marla Muttlesworth.

Susan quickly achieved distinction in the Denver design community as a forward-thinking web developer whose work is both creative and consistent. Q Digital Studio is founded on principals of sustainability and integrity, values that are near and dear to Susan's heart.

When Susan's not planning design conferences or fearlessly leading the Q Digital Studio team, she enjoys cooking and watching movies.

Follow Susan on Twitter @SusanSnipes.