Compress a PDF file

Table of contents:

Compress a PDF file
Compress a PDF file

Files in the 'Portable Document Format' (pdf) format are easy to use because it does not matter which operating system the recipient has. With Adobe Reader a PDF can always be read. Of course it depends on the content, but a PDF can become very large and then it takes a long time to download. Read this article to learn how to make a PDF smaller without losing any information.


Method 1 of 5: Using online tools

Compress a PDF File Step 1

Step 1. Search online for a conversion website

Use the following search term: 'free online pdf compression'. Only use free websites and check which sites are recommended first.

Compress a PDF File Step 2

Step 2. Select the file you want to compress or drag the file into the window to start uploading

You may need to view an ad or enter a captcha code.

Compress a PDF File Step 3

Step 3. Wait

When the compression is complete, the message that you can download the file will appear. In some cases you will receive an email with the compressed file, in other cases you can download it directly from the site.

Method 2 of 5: Using the 'Smaller PDF' feature in Adobe Acrobat

Compress a PDF File Step 4

Step 1. Open the PDF file you want to compress in Adobe Acrobat

You can also select multiple PDF files at once.

Compress a PDF File Step 5

Step #2. Click on File → Save As → Smaller PDF

Select the desired version compatibility. If you choose newer versions, you will get smaller files, but you won't be able to open the file with older versions of Acrobat.

Method 3 of 5: Using Preview on an Apple computer

Compress a PDF File Step 6

Step 1. Open the PDF file in Preview by double clicking it in the Finder menu

PDF files are likely to open automatically with Preview. Otherwise, you can pick up the PDF file and drag it to the Preview icon in your Dock

Compress a PDF File Step 7

Step #2. Click on File → Save As

A window opens.

Compress a PDF File Step 8

Step 3. Click on the Quartz Filter menu and select 'Reduce File Size'

Compress a PDF File Step 9

Step 4. Save the file

Choose the desired location and click on 'Save'. If you do not rename the file, you will now be asked if you want to replace the old file with the compressed file.

Method 4 of 5: Using the Optimize PDF feature in Adobe Acrobat

Compress a PDF File Step 10

Step 1. Save your file as 'Optimized PDF'

Select File > Save As > Optimized PDF. A window will now appear with a number of options.

Compress a PDF File Step 11

Step 2. See which part makes the file large

Click the 'Check space usage' button at the top of the dialog box. Now you see per part stated how big it is in the number of bytes and as the percentage of the whole. You can see from this whether the size is perhaps mainly determined by the images, or for example by the fonts. Adjust the settings. Use the default settings or adjust to your liking. Use the menu on the left to view different aspects of the file.

Compress a PDF File Step 12

Step 3. Go to the 'Images' window to adjust the images in your document

Options are available for compression and downsampling of color, grayscale, and monochrome images.

  • The higher the number of ppi (pixels per inch), the better the resolution. But if you're not going to print, it's better to set a lower ppi (this results in a smaller file). You only need 72 ppi for sufficient screen quality.
  • Downsampling reduces file size by decreasing the resolution of images, merging the colors of the original pixels into larger pixels. Choose the desired option from the drop-down window. Choose 'Average Downsampling', 'Subsampling' or 'Bicubic Downsampling'. The last option gives gradual gradations.
Compress a PDF File Step 13

Step 4. Click on 'Fonts' to choose whether or not to embed fonts

Embedding a font ensures that the receiving party will see the document in the same way, even if he or she doesn't have that font installed on the computer.

Don't embed the fonts if it doesn't matter if the exact font is used. The file will then become smaller. The fonts are automatically replaced. The Fonts pane of the Optimize PDF dialog box contains two lists of fonts: unembeddable fonts, and embedded fonts to remove

Compress a PDF File Step 14

Step 5. Go to the 'Transparency' window to flatten the transparency and reduce the file size

Flattening incorporates transparency into the artwork by dividing the artwork into vector areas and rasterized areas. PDF Optimizer applies transparency options to all pages in the document before applying other optimization options.

Compress a PDF File Step 15

Step 6. Go to the 'Ignore objects' window to specify which objects to remove from the PDF

The objects you're ignoring may have been created in Acrobat and other applications. Selecting an object removes all instances of that object from the PDF. Options include: 'Ignore all JavaScript actions', 'Recognize and merge image fragments' and 'Ignore bookmarks'.

Compress a PDF File Step 16

Step 7. Go to the 'Ignore User Data' window to remove personal data that you do not want to distribute or share with others

Here too you can check various options. Choose from options like "Ignore all comments, forms, and multimedia," "Ignore document data and metadata," and "Ignore private data from other applications."

Personal information may be hidden. If you can't find any personal information, it may be hidden. You can find hidden text and other user-related information using the 'Review Document' command in the 'Document' menu

Compress a PDF File Step 17

Step 8. Go to the 'Delete Unnecessary Settings' window to delete unnecessary items from the document

Make sure 'Compress document structure' is checked.

Only elements that do not affect functionality are selected by default. Use the default selections if you don't know the consequences of removing other options

Compress a PDF File Step 18

Step 9. Click OK

The file will now be converted according to the rules of your new settings. Choose a file name, location and format (pdf).

Method 5 of 5: Using PDF Compressor

Step 1. Go to PDF Compressor

Compress pdf files online step1

Step 2. Click 'UPLOAD FILES' to select PDF documents on your computer or drag and drop them into the window

You can upload up to 20 files at a time.

Compress pdf files online step2

Step 3. Wait for the compression to finish

Compress pdf files online step3

Step 4. Download each file one by one or click 'DOWNLOAD ZIP' to download all files at once as ZIP archive


  • Using one font makes for a smaller file.
  • Transparency flattening cannot be undone after the file is saved.

Popular by topic