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Reduce PDF File Size Below 100 KB Online

by Hung Nguyen

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The best free online tool to compress large PDFs while maintaining both file format and quality. No registration or download needed.

Millions of people visit our website daily to use our conversion tools. But what we really love above all else is compressing PDFs. After all, that’s where it all started, way back in 2013, and where we got our name. So, if you need to significantly reduce PDF file size to below 100 KB, you’re on the right platform.

Compressing PDF files can be effortless when you know where to look. Here’s how you can do it yourself within a few seconds.

How to Reduce PDF File Size Below 100 KB for Free

  1. Go to the Compress PDF tool.

  2. Drag and drop your PDF in.

  3. Choose the compression type and click “Compress.”

  4. Wait for the PDF compression tool to shrink the file.

  5. Download your teeny-tiny PDF.

Reduce PDF File Size Below 100 KB Online

Reducing PDF files to below 100 KB, just for your needs

How Big a File Can You Take?


The maximum file size that our online PDF compressor can manage is 5 GB per file. That means that there are very few PDF documents out there that our tool can’t handle. After all, the “P” in PDF does stand for “portable.” The final size of your file as well as the compression rate we achieved, will be displayed on the result page. And yes, it’s free to use! Plus, we don’t add annoying watermarks to your file—it will look just as it did before.

What About the Quality of My Files?


Quality retention is a guarantee. The file size reducer tool works on large PDF documents by scanning each file, identifying similar data patterns, and replacing all the duplicates with a unique identifier. Each of these identifiers is much smaller in comparison to the original content of the PDF, and thus, the size is considerably smaller.

Batch Processing & Stronger Compression


With a Smallpdf Pro subscription, you get access to batch processing. That means you can drag and drop as many files as you’d like into the toolbox and process them at the same time. It’s the ideal solution for winning back some storage space without spending hours compressing individual PDFs. A Pro account also provides you with access to our strong compression mode. This powerful option can reduce your PDF file size by up to 75%! If you’d like to test it out without committing to anything, sign up for a free trial of Smallpdf Pro today—you can cancel anytime.

Further Modification


Make your PDF look absolutely perfect with the rest of our tool suite. They are just as fast, effective, and easy to use as our PDF compressor—and of course, free of charge! Here are a few other guides to get you started:

  • PDF to Word - Transform PDFs into Microsoft Word files to make edits.
  • Word to JPG - Turn your text files into the most popular image format.
  • Add Pages - Complete your PDF by adding missing pages quickly.
  • PDF Scanner - Scan and convert any image to a PDF using your mobile.
  • Sign PDF - E-sign your documents and contracts in seconds.
  • PDF Converter - Convert any file—JPG, Word, Excel, and more—to and from PDF.
small but just as efficient

Small PDF files, but just as efficient.

Hung Nguyen
Hung Nguyen
Senior Growth Marketing Manager @Smallpdf