Why Reduce File Size Makes an Acrobat PDF Larger & How to Fix It
Question details
The user is trying to compress a PDF document, but finds that utilizing the 'Reduce File Size' feature actually results in a larger file than the original optimized version.
- Product
- Adobe Acrobat
- Device & OS
- not provided
- Scenario
- Compressing and optimizing an existing PDF file to reduce its storage footprint.
- Observed behavior
- Applying the 'Reduce File Size' command inflates the document's file size instead of performing further compression.
Before modifying your PDF settings, ensure you keep a backup copy of your original document so you can safely experiment with different compression parameters without losing image quality.
Avoid Redundant Compression and Use Custom Optimize Settings
Understand how the 'Reduce File Size' preset works and switch to granular optimization settings to ensure your file actually decreases in size.
The 'Reduce File Size' tool in Adobe Acrobat is not an additional stage of magic compression. Instead, it acts as an 'Optimize PDF' preset with standard default settings. If you have already compressed your PDF using carefully customized settings, running 'Reduce File Size' afterward replaces your custom parameters with its default ones, which is the primary reason your file size increases.
To properly shrink your document, you should skip the preset and manually configure the detailed optimization options.
Open your document in Adobe Acrobat. Go to the 'Tools' menu at the top of the interface and select the 'Optimize PDF' tool.
In the secondary toolbar, avoid clicking 'Reduce File Size'. Instead, click on 'Advanced Optimization' to launch the detailed PDF Optimizer dialog box.
Review the settings across the side panels (Images, Fonts, Transparency, Discard Objects). Manually set the Image downsampling pixels-per-inch (PPI) to a lower value than your document currently uses, and choose to unembed unnecessary fonts.
Click 'OK' once you have configured your settings. Choose 'Save As' to export the file as a separate copy, allowing you to compare the new file size with your original document.
Compress PDFs Effortlessly with WPS Office
Avoid confusing compression presets and unexpected file size increases. WPS Office provides a straightforward PDF compression tool that reliably reduces file size while maintaining excellent document clarity.
- 1. Open your PDF in WPS Office: Launch WPS Office and open the PDF document you wish to compress.
- 2. Select the Compress Tool: Navigate to the 'Tools' tab on the top ribbon menu and click on the 'Compress' button.
- 3. Choose a Compression Level: Select your desired compression tier (such as HD, Normal, or Common) depending on how much you need to shrink the file and your quality requirements.
- 4. Process and Save: Click 'Compress' to process the document. Once finished, save the newly reduced PDF file to your local drive.
Frequently Asked Questions
Can I undo a 'Reduce File Size' action if my PDF becomes larger?
Yes. As long as you have not saved and closed the document, you can use the Undo shortcut (Ctrl+Z or Cmd+Z) to revert the change. Alternatively, you can close the document without saving and reopen your original file.
Which settings have the biggest impact on reducing PDF file size?
Image downsampling and font unembedding typically have the most significant impact. High-resolution images often account for the majority of a PDF's storage size. Lowering the image PPI (pixels per inch) yields the best compression results.
Why does a PDF sometimes increase in size simply by doing a 'Save As'?
Saving a PDF can sometimes append new metadata, version history, or re-encode elements according to the editor's default settings. If the software rewrites highly compressed elements into a less efficient format, the overall file size will increase.
