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Optimizing PDFs

  1. Acrobat User Guide
  2. Introduction to Acrobat
    1. Access Acrobat from desktop, mobile, web
    2. Introducing the new Acrobat experience
    3. What's new in Acrobat
    4. Keyboard shortcuts
    5. System Requirements
  3. Workspace
    1. Workspace basics
    2. Opening and viewing PDFs
      1. Opening PDFs
      2. Navigating PDF pages
      3. Viewing PDF preferences
      4. Adjusting PDF views
      5. Enable thumbnail preview of PDFs
      6. Display PDF in browser
    3. Working with online storage accounts
      1. Access files from Box
      2. Access files from Dropbox
      3. Access files from OneDrive
      4. Access files from SharePoint
      5. Access files from Google Drive
    4. Acrobat and macOS
    5. Acrobat notifications
    6. Grids, guides, and measurements in PDFs
    7. Asian, Cyrillic, and right-to-left text in PDFs
  4. Creating PDFs
    1. Overview of PDF creation
    2. Create PDFs with Acrobat
    3. Create PDFs with PDFMaker
    4. Using the Adobe PDF printer
    5. Converting web pages to PDF
    6. Creating PDFs with Acrobat Distiller
    7. Adobe PDF conversion settings
    8. PDF fonts
  5. Editing PDFs
    1. Edit text in PDFs
    2. Edit images or objects in a PDF
    3. Rotate, move, delete, and renumber PDF pages
    4. Edit scanned PDFs
    5. Enhance document photos captured using a mobile camera
    6. Optimizing PDFs
    7. PDF properties and metadata
    8. Links and attachments in PDFs
    9. PDF layers
    10. Page thumbnails and bookmarks in PDFs
    11. PDFs converted to web pages
    12. Setting up PDFs for a presentation
    13. PDF articles
    14. Geospatial PDFs
    15. Applying actions and scripts to PDFs
    16. Change the default font for adding text
    17. Delete pages from a PDF
  6. Scan and OCR
    1. Scan documents to PDF
    2. Enhance document photos
    3. Troubleshoot scanner issues when scanning using Acrobat
  7. Forms
    1. PDF forms basics
    2. Create a form from scratch in Acrobat
    3. Create and distribute PDF forms
    4. Fill in PDF forms
    5. PDF form field properties
    6. Fill and sign PDF forms
    7. Setting action buttons in PDF forms
    8. Publishing interactive PDF web forms
    9. PDF form field basics
    10. PDF barcode form fields
    11. Collect and manage PDF form data
    12. About forms tracker
    13. PDF forms help
    14. Send PDF forms to recipients using email or an internal server
  8. Combining files
    1. Combine or merge files into single PDF
    2. Rotate, move, delete, and renumber PDF pages
    3. Add headers, footers, and Bates numbering to PDFs
    4. Crop PDF pages
    5. Add watermarks to PDFs
    6. Add backgrounds to PDFs
    7. Working with component files in a PDF Portfolio
    8. Publish and share PDF Portfolios
    9. Overview of PDF Portfolios
    10. Create and customize PDF Portfolios
  9. Sharing, reviews, and commenting
    1. Share and track PDFs online
    2. Mark up text with edits
    3. Preparing for a PDF review
    4. Starting a PDF review
    5. Hosting shared reviews on SharePoint or Office 365 sites
    6. Participating in a PDF review
    7. Add comments to PDFs
    8. Adding a stamp to a PDF
    9. Approval workflows
    10. Managing comments | view, reply, print
    11. Importing and exporting comments
    12. Tracking and managing PDF reviews
  10. Saving and exporting PDFs
    1. Saving PDFs
    2. Convert PDF to Word
    3. Convert PDF to JPG
    4. Convert or export PDFs to other file formats
    5. File format options for PDF export
    6. Reusing PDF content
  11. Security
    1. Enhanced security setting for PDFs
    2. Securing PDFs with passwords
    3. Manage Digital IDs
    4. Securing PDFs with certificates
    5. Opening secured PDFs
    6. Removing sensitive content from PDFs
    7. Setting up security policies for PDFs
    8. Choosing a security method for PDFs
    9. Security warnings when a PDF opens
    10. Securing PDFs with Adobe Experience Manager
    11. Protected View feature for PDFs
    12. Overview of security in Acrobat and PDFs
    13. JavaScripts in PDFs as a security risk
    14. Attachments as security risks
    15. Allow or block links in PDFs
  12. Electronic signatures
    1. Sign PDF documents
    2. Capture your signature on mobile and use it everywhere
    3. Send documents for e-signatures
    4. Create a web form
    5. Request e-signatures in bulk
    6. Collect online payments
    7. Brand your account
    8. About certificate signatures
    9. Certificate-based signatures
    10. Validating digital signatures
    11. Adobe Approved Trust List
    12. Manage trusted identities
  13. Printing
    1. Basic PDF printing tasks
    2. Print Booklets and PDF Portfolios
    3. Advanced PDF print settings
    4. Print to PDF
    5. Printing color PDFs (Acrobat Pro)
    6. Printing PDFs in custom sizes
  14. Accessibility, tags, and reflow
    1. Create and verify PDF accessibility
    2. Accessibility features in PDFs
    3. Reading Order tool for PDFs
    4. Reading PDFs with reflow and accessibility features
    5. Edit document structure with the Content and Tags panels
    6. Creating accessible PDFs
    7. Cloud-based auto-tagging
  15. Searching and indexing
    1. Creating PDF indexes
    2. Searching PDFs
  16. Multimedia and 3D models
    1. Add audio, video, and interactive objects to PDFs
    2. Adding 3D models to PDFs (Acrobat Pro)
    3. Displaying 3D models in PDFs
    4. Interacting with 3D models
    5. Measuring 3D objects in PDFs
    6. Setting 3D views in PDFs
    7. Enable 3D content in PDF
    8. Adding multimedia to PDFs
    9. Commenting on 3D designs in PDFs
    10. Playing video, audio, and multimedia formats in PDFs
    11. Add comments to videos
  17. Print production tools (Acrobat Pro)
    1. Print production tools overview
    2. Printer marks and hairlines
    3. Previewing output
    4. Transparency flattening
    5. Color conversion and ink management
    6. Trapping color
  18. Preflight (Acrobat Pro)
    1. PDF/X-, PDF/A-, and PDF/E-compliant files
    2. Preflight profiles
    3. Advanced preflight inspections
    4. Preflight reports
    5. Viewing preflight results, objects, and resources
    6. Output intents in PDFs
    7. Correcting problem areas with the Preflight tool
    8. Automating document analysis with droplets or preflight actions
    9. Analyzing documents with the Preflight tool
    10. Additional checks in the Preflight tool
    11. Preflight libraries
    12. Preflight variables
  19. Color management
    1. Keeping colors consistent
    2. Color settings
    3. Color-managing documents
    4. Working with color profiles
    5. Understanding color management

Before you begin

We are rolling out a new, more intuitive product experience. If the screen shown here doesn’t match your product interface, switch to the help for your current experience.

Acrobat reduces the size of a PDF file without compromising quality. The Acrobat PDF compression tool balances an optimized file size against the expected quality of images, fonts, and other file content.

Save using PDF optimizer (Acrobat Pro)

PDF Optimizer provides many settings for reducing the size of PDF files. Some of the PDF Optimizer settings are comparable to the settings that are available when you create a PDF file using Distiller. You can use all of these settings or only a few. It depends on how you intend to use the files and the essential properties a file must have.

Usually, the default settings are suitable for achieving maximum efficiency. It includes saving space by removing embedded fonts, compressing images, and removing redundant items from the file. Before optimizing a file, it’s a good idea to audit its space usage. The space audit results may provide insights into the possibilities of reducing file size. You can also reduce the size of your PDF by using the Reduce File Size command.

  • Some methods of compression may make images unusable in a print production workflow. You should experiment with various settings before making changes that can’t be discarded.
  • The PDF Optimizer isn’t available when Reflow is selected in the View menu.

Audit the space usage of a PDF (Acrobat Pro)

The space usage audit reports the total number of bytes used for specific document elements. It includes fonts, images, bookmarks, forms, named destinations, comments, and the total file size. The results are reported in bytes and as a percentage of the total file size.

  1. From the hamburger menu  (Windows) or the File menu (macOS), select Save As Other > Optimized PDF, or go to All tools > Compress a PDF, and then select Advanced Optimization. The PDF Optimizer dialog opens.

  2. Select Audit space usage in the dialog.


You can also audit space usage of a PDF in the Content pane. Choose the hamburger menu  (Windows) > View, or the View menu (macOS) and then select Show/Hide > Side panels > Content. From the Content pane options menu, choose Audit Space Usage.

Optimize a PDF (Acrobat Pro)

  1. Open a PDF in Acrobat.

  2. From the hamburger menu  (Windows) or the File menu (macOS), select Save As Other > Reduced Size PDF.

  3. Choose the location to save the file and select Save. Acrobat displays a message showing the successful reduction in PDF size.

  1. Go to All tools > Compress a PDF and select Multiple files.

  2. In the Arrange documents dialog, select Add Files > Add Files.

    Select and add files

  3. In the Add Files dialog, select the files you want to add, and confirm.

  4. Select the desired version compatibility, and then select OK.


    If you’re certain that all your users use Acrobat or Acrobat Reader, limiting compatibility to the latest version can further reduce file size.

  5. In the Output Options dialog, specify your folder and filename preferences.

  1. From the hamburger menu  (Windows), or the File menu (macOS), select Save As Other > Optimized PDF, or go to All tools > Compress a PDF, and then select Advanced Optimization. The PDF Optimizer dialog opens.

  2. To use the default settings, choose Standard from the Settings menu, and then skip to step 6. If you change any settings in the PDF Optimizer dialog box, the Settings menu automatically switches to Custom.

  3. From the Make compatible with menu, choose Retain existing to keep the current PDF version, or choose an Acrobat version. (The options available in panels vary depending on this choice.)

  4. Select the check box next to a panel (for example, Images, Fonts, Transparency), and then select options in that panel. To disable options in a panel, deselect the corresponding check box.

  5. (Optional) To save your customized settings, select Save and name the settings. (To delete a saved setting, choose it in the Settings menu and select Delete.)

  6. After choosing the desired options, select OK.

  7. In the Save Optimized As dialog box, select Save to overwrite the original PDF with the optimized PDF, or select a new name or location.


    To optimize several documents at the same time, use the Output options for the Actions wizard.

PDF Optimizer options (Acrobat Pro)

Use the options from the panels in the PDF Optimizer dialog box to reduce the size of a PDF.

Images panel

The Images panel of the PDF Optimizer lets you set options for color, grayscale, and monochrome image compression, and image downsampling.

PDF Optimizer options in Acrobat
Change the PDF compatibility in the Images panel of the PDF Optimizer dialog box in Acrobat Pro.

Specify the following options, as needed:


Reduces file size by lowering the resolution of images, which involves merging the colors of original pixels into larger pixels.

Note: Masked images and images with a size less than 16-by-16 pixels aren't downsampled.


Reduces file size by eliminating unnecessary pixel data. In general, JPEG and JPEG 2000 compressions yield better results on images, such as photographs with gradual transitions from color to color. ZIP is the better choice for illustrations with large areas of solid, flat colors, or patterns of flat colors. For monochrome images, JBIG2 compression is available in PDF Optimizer but not in Distiller, and it's superior to CCITT.


Available only for JPEG and JPEG 2000 formats. JPEG and JPEG 2000 compression methods are typically lossy, a process that permanently removes some pixel data. You can apply lossy JPEG or JPEG 2000 compression to color images at various levels (Minimum, Low, Medium, High, Maximum). For JPEG 2000 compression, you can also specify lossless so that no pixel data is removed. Compression for monochrome images is lossless, except for JBIG2 compression, which provides both Lossy and Lossless modes of compression.

Tile size

Available only for JPEG 2000 format. Divides the image being compressed into tiles of the given size. (If the image height or width isn't an even multiple of the tile size, partial tiles are used on the edges.) Image data for each tile is individually compressed and can be individually decompressed. The default value of 256 is recommended.

Optimize images only if there is a reduction in size

When selected, if the image setting will cause an increase in file size, the optimization for that image is skipped.

Fonts panel

To ensure an exact match to the source document, embed all fonts used. If you don’t require an exact match and prefer a smaller file, skip embedding fonts for Roman and East Asian text (Traditional Chinese, Simplified Chinese, Korean, and Japanese). Text in these languages is replaced with a substitution font when viewed on a system without original fonts. The Fonts panel of the PDF Optimizer contains two lists for fonts: fonts that are available for unembedding and fonts to unembed. Specific fonts aren’t available for unembedding and don’t appear in the Fonts panel. Select one or more fonts in a document in the Embedded Fonts list and select the Unembed button to unembed fonts in a document. If you don’t want to embed subsets of the embedded fonts, deselect Subset All Embedded Fonts. Select Do Not Unembed Any Font to prevent unembedding for all fonts in the document.

Transparency panel

If your PDF includes artwork with transparency, use presets in the Transparency panel of PDF Optimizer to flatten transparency and reduce file size. (Flattening incorporates transparency into corresponding artwork by sectioning it into vector-based areas and rasterized areas.) PDF Optimizer applies transparency options to all pages in the document before applying other optimization options.

If you select the Acrobat 4.0 And Later compatibility setting, the Transparency panel is enabled, and all transparency in the file is flattened during optimization. It ensures compatibility with Acrobat 4.0 and earlier, which doesn’t support transparency.

When you create flattening presets, they appear with the default presets in the Transparency panel.


Transparency flattening can't be undone after the file is saved.

Discard Objects panel

The Discard Objects panel lets you specify objects to remove from the PDF and lets you optimize curved lines in CAD drawings. You can discard objects created in Acrobat and in other applications. Selecting an object removes all occurrences of that object within the PDF.

In the Discard Objects area, you can select from these and other options:

Discard all form submission, import and reset actions

Disables all actions related to submitting or importing form data, and resets form fields. This option retains form objects to which actions are linked.

Flatten form fields

Makes form fields unusable with no change to their look and feel. Form data is merged with the page to become page content.

Discard all JavaScript actions

Removes any actions in the PDF that use JavaScript.

Discard all alternate images

Removes all versions of an image except the one destined for onscreen viewing. Some PDFs include multiple versions of the same image for different purposes, such as low-resolution onscreen viewing and high-resolution printing.

Discard embedded page thumbnails

Removes embedded page thumbnails. It's useful for large documents, which can take a long time to draw page thumbnails after you select the Page Thumbnails button.

Discard document tags

Removes tags from the document, which also removes the accessibility and reflow capabilities for the text.

Convert smooth lines to curves

Reduces the number of control points used to build curves in CAD drawings, which result in smaller PDF files and faster onscreen rendering.

Detect and merge image fragments

Looks for images or masks that are fragmented into thin slices and tries to merge the slices into a single image or mask.

Discard embedded print settings

Removes embedded print settings, such as page scaling and duplex mode, from the document.

Discard embedded search index

Removes embedded search indexes, which reduces the file size.

Discard bookmarks

Removes all bookmarks from the document.

Discard User Data panel

Use the Discard User Data panel to remove any personal information that you don’t want to distribute or share with others. If you’re unable to find personal information, it may be hidden. You can locate hidden text and user-related information by using the Examine Document command (All toolsRedact a PDF > Sanitize Document, and then choose to remove hidden information).

Discard all comments, forms and multimedia

Removes all comments, forms, form fields, and multimedia from the PDF.


Discard document information and metadata

Removes information in the document information dictionary and all metadata streams. (Use the Save As command to restore metadata streams to a copy of the PDF.)


Discard all object data

Removes all objects from the PDF.


Discard file attachments

Removes all file attachments, including attachments added to the PDF as comments. (PDF Optimizer doesn’t optimize attached files.)


Discard external cross references

Removes links to other documents. Links that jump to other locations within the PDF aren't removed.


Discard private data of other applications

Strips information from a PDF document that is useful only to the application that created the document. It doesn't affect the functionality of the PDF, but it does decrease the file size.


Discard hidden layer content and flatten visible layers

Decreases file size. The optimized document looks like the original PDF but contains no layer information.

Clean Up panel

The options in the Clean Up panel of the PDF Optimizer dialog let you remove redundant items from the document. It includes obsolete or unnecessary elements for your intended use of the document. Removing certain elements can seriously affect the functionality of the PDF. By default, only elements that don't affect functionality are selected. Use the default selections if you're unsure of the implications of removing other options.

Object compression options

Specifies how to apply Flate compression in the file.

Use Flate to encode streams that are not encoded

Applies Flate compression to all streams that aren’t encoded.

In streams that use LZW Encoding, use Flate instead

Applies Flate compression to all content streams and images that use LZW encoding.

Discard invalid bookmarks

Removes bookmarks that point to pages in the document that have been deleted.

Discard invalid links

Removes links that jump to invalid destinations.

Discard unreferenced named destinations

Removes named destinations not referenced internally from within the PDF document. Because this option doesn't check for links from other PDF files or websites, it doesn't fit in some workflows.

Optimize page content

Converts all the end-of-line characters to spaces, which improves Flate compression.

Optimize the PDF for fast web view

Restructures a PDF document for page-at-a-time downloading (byte-serving) from web servers.

Enable Fast Web View in a PDF

Fast Web View restructures a PDF document for page-at-a-time downloading (byte-serving) from web servers. With Fast Web View, the web server sends only the requested page, rather than the entire PDF. This option is especially important with large documents that can take a long time to download from a server.

Check with your webmaster to ensure the web server software supports page-at-a-time downloading. To ensure that the PDF documents on your website appear in older browsers, create HTML links (versus ASP scripts or the POST method) to the documents. Also, use shorter path names (256 characters or fewer).

Verify that an existing PDF is enabled for Fast Web View

  1. Open the PDF in Acrobat. From the hamburger menu , select Document Properties. Look in the lower-right area of the Description panel of the dialog box for the Fast Web View setting (yes or no).

Verify the Fast Web View Preferences setting

Follow this procedure to make sure that you have Acrobat set up to enable Fast Web View during the PDF creation process.

  1. In the Preferences dialog box under Categories, select Documents.

  2. On the right side of the dialog box, under Save Settings, make sure that Save As Optimizes For Fast Web View is selected, and select OK.

Enable Fast Web View for an existing PDF

Use this procedure after you've verified your Fast Web View Preferences setting and checked the PDF properties to ensure the file isn't already enabled for Fast Web View.

  1. Open the PDF. From the hamburger menu  (Windows) or the File menu (macOS), choose Save As. Select the same filename and location.

  2. When a message appears asking if you want to overwrite the existing file, select OK.


In Acrobat Pro, you can also quickly enable Fast Web View in entire folders of Adobe PDF files by using the Prepare for Web Publishing action. See Run an action.


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