Written By JSB (Jason Brown)
Last updated 27 days ago
We’re sharing this guide to help you reduce the size of large PDF files—especially if you’re using our document Signature feature, which has a file size limit of 40MB and 500 pages. We can’t do much about files with too many pages, but if your document is under the page limit and still too large, compression might help.
Before we jump in:
Digs does not officially recommend or endorse any specific PDF compression site, tool, or service. Any products mentioned below are for demonstration purposes only, and we encourage you to choose the method that best fits your comfort level and privacy needs.
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Why Are Some PDFs So Large?
PDFs are made up of lots of components—images, text, fonts, formatting data, and sometimes embedded data like print settings or accessibility layers. If it’s a PDF/A formatted document (often used for archiving), it includes extra metadata to ensure the file always looks the same, no matter where or when it’s opened.
Some of this content, like structural formatting or embedded fonts, can’t really be compressed. Other parts—like images—can be reduced in size, but may lose quality. Occasionally, a file simply can’t be compressed effectively due to its structure or internal errors. It’s rare, but it happens.
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Your Options for Shrinking a PDF
There are three main ways to reduce PDF size: Native tools, Online tools, and Third-party software. Each comes with pros and cons.
1. Native Tools (Built into Your Computer)
• On a Mac, the built-in Preview app lets you export a smaller file by choosing File > Export > Quartz Filter: Reduce File Size.
• This is quick and easy for basic PDFs, but it may not handle complex or image-heavy documents well. Good in a pinch, but not always the best solution.
2. Third-Party Software
• Tools like PDF Expert, UPDF, or Adobe Acrobat Pro can compress files reliably and may offer more control over output quality.
• Many of these tools require a paid license, which may not be ideal if you’re just compressing a single file.
• Adobe Acrobat Pro also offers a free trial that includes compression capabilities.
3. Online Compression Tools
• These are fast, often free, and easy to use—perfect for one-time tasks.
• However, always use caution: Never upload PDFs that include sensitive or personal data to unknown or untrusted sites. Not all of them are secure or transparent about how they handle your files.
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A Note on Adobe’s Online Tool
While Digs doesn’t officially recommend any single tool, it’s worth noting that Adobe —the creator of the PDF format— offers a free online compression tool. At the time of writing, it successfully compressed a 300MB file to around 13MB in (High compression/Standard quality), 36MB in (Medium comp./Better quality), or 56MB (Highest Comp./Best quality). Adobe states that uploaded files are not stored, making it a potentially safer option compared to random third-party sites.
You can try it here: