Compressing a PDF, which can be very large if they have hundreds of pages, reduces its file size, making it easier to store, share, and manage. Needless to say, smaller PDF files upload and download more quickly, saving time and improving efficiency, especially when dealing with large documents or multiple files.

A few benefits if a large PDF file size is reduced:

Many email services have attachment size limits, so compressing a PDF allows you to send large documents via email without exceeding these limits, preventing bouncebacks or failed deliveries.
Compressed PDFs are easier to open and read on mobile devices, which often have less processing power and storage capacity compared to desktop computers.
Smaller PDF files load faster in web browsers and PDF readers, which provides a better user experience when accessing documents online.
For organisations that pay for data storage or bandwidth, reducing the size of PDFs can result in cost savings over time.
Some systems and applications may have file size restrictions, and compressing PDFs ensures that your documents meet these requirements, ensuring compatibility.

The benefits are clear, but how to reduce the size of a large PDF file? That’s what we’re about to find out.

Reduce a PDF Size for Free with 4K Image Compressor (Windows, Mac, Ubuntu)

You can easily compress any PDF document with 4K Image Compressor, a desktop tool for Windows, macOS, and Ubuntu devices. In addition to reducing PDF files’ sizes, it can also compress JPEG, HEIC, WEBP, and PNG images and can do it in bulk. Here are the steps to follow:

1. Launch 4K Image Compressor.

2. In the menu bar, click Format and select PDF, or leave the default selection as "Same as Input."

3. Click on the Optimization section and choose Auto from the drop-down list.

4. Click the settings icon next to Optimization. In the opened window, select one of the Auto Optimization presets, or enable the Manual mode. If using Manual mode, adjust the PDF Quality slider according to your preference.

5. Click the Compress button in the middle of the application window to select your file, or simply drag and drop the file into the application. Your PDF will be immediately uploaded and compressed.

How to Compress a PDF File on Windows PC

How to Compress a PDF in Adobe Acrobat Pro

You can use Adobe Acrobat Pro on your PC to compress multiple PDFs offline. Follow these steps:

Open Adobe Acrobat Pro and launch the "Optimize PDF" tool.
Find and open your PDF by clicking "Open."
Click the "Reduce File Size" button in the top menu.
Choose your desired compatibility option and click "OK."
Rename your file if needed, then click "Save."

Use Microsoft Word

Not many know that this text-editing software can also compress PDF files. Here’s how:

Open an existing PDF or a Word document to use this compression tool. Note that opening a PDF in Word may alter its original formatting.
Click the File menu at the top-left corner of the window.
Export the document:

On Windows: Click Export, then select Create PDF/XPS.
On Mac: Click Save As.

Select PDF format:

On Windows: Ensure that "PDF" is selected next to "Save as type."
On Mac: Select "PDF" as the File Format near the bottom of the window.

Choose an optimization option:

On Windows: At the bottom of the window, choose Minimum size to compress the PDF to a smaller size.
On Mac: Select Best for electronic distribution and accessibility for compression.

6. To overwrite the existing PDF file, keep the same name and folder. Otherwise, modify the file name and/or choose a different folder.

7. Save the compressed PDF:

On Windows: Click Publish.
On Mac: Click Export.

Your compressed PDF will now be saved in the selected location.

How to Compress a PDF on Mac

Use Preview

You can easily compress PDFs on your Mac using the Preview app. Here's how:

Open your PDF file in Preview.
Click "File" in the menu bar.
Select "Export..." from the drop-down menu. (Avoid selecting "Export as PDF" as it won't allow you to compress the file.)

Optionally, type a new name for the compressed PDF next to "Export As."

From the "Quartz Filter" menu, select "Reduce File Size."

Use the drop-down menu next to "Where:" to select the location where you want to save the compressed PDF. By default, it will be saved to your desktop.
Click "Save." Your compressed PDF will be saved in the selected location on your Mac.

Your compressed PDF is now saved on your Mac, taking up less storage space and making it easier to share.

How to Compress a PDF for Free: Online Methods

Use Adobe Acrobat Online PDF Compressor

You can easily compress PDFs on the go with the Adobe Acrobat online PDF compressor.

Here’s a simple guide:

Open your browser and go to the Acrobat online PDF compressor.
Click "Select a File" to find your PDF, or drag and drop your PDF into the designated Compress PDF area.
Once the compression is complete, download your newly compressed PDF.

Some other ways to make a PDF file size smaller online is to use tools like iLovePDF, SmallPDF Pro, or PDF2Go.

That's it! Whether you choose 4K Image Compressor, Adobe software, Preview, or an online tool, your PDF file is ready to be shared per email, uploaded and stored without taking too much space.