How to Compress a PDF File to a Smaller Size

The fastest way to compress a PDF depends on what you have

You can compress a PDF on your computer using built-in tools, online converters, or dedicated software — the right choice depends on file size, how much compression you need, and whether you want to keep the file offline. Most people can shrink a PDF by 30 to 50 percent without visible quality loss, though compressing images inside the PDF trades file size for sharpness.

On Windows, you can use the built-in Print to PDF feature to re-save at lower quality. On Mac, Preview handles compression directly. Online tools like Smallpdf, ILovePDF, or PDF Compressor work from any browser but upload your file to their servers. Desktop software like Adobe Acrobat Pro, PDFtk, or Ghostscript gives you the most control but costs money or requires installation.

Key Takeaways

Windows users can compress PDFs by printing to PDF and selecting lower quality settings, which costs nothing and keeps files offline.
Mac users can open a PDF in Preview, go to File > Export, and choose Quartz Filter to reduce file size without extra software.
Online tools like Smallpdf or ILovePDF work on any device but require uploading your file to the internet.
Compressing a PDF usually shrinks image quality noticeably; text-heavy PDFs compress better than image-heavy ones.
Adobe Acrobat Pro and Ghostscript offer the most control over compression settings but require purchase or installation.

Compress on Windows using Print to PDF

Open the PDF in any program that can read it — Adobe Reader, your web browser, or Microsoft Edge all work. Click File, then Print. In the printer dropdown, select "Print to PDF" or "Microsoft Print to PDF" (the exact name depends on your Windows version). Click Print.

A save dialog opens. Before you save, look for a button labeled "More settings," "Options," or "Preferences" — this is where you control quality. Set the quality to "Low" or "Draft" to shrink the file most; "Medium" or "Standard" balances size and readability. Save the new PDF. The compressed version will be smaller than the original, though images will look softer.

Compress on Mac using Preview

Open the PDF in Preview (the default PDF reader on Mac). Click File in the menu bar, then Export. A dialog box appears with export options.

Look for a dropdown labeled "Quartz Filter" — this is where compression happens. Select "Reduce File Size" from the dropdown. Click Save. Preview will compress the PDF and save it with a new name. The original stays unchanged. This method works well for PDFs with many images and usually cuts file size by 40 to 60 percent, though image sharpness drops.

Use an online tool if you want to avoid installation

Smallpdf, ILovePDF, and PDF Compressor are three common online options. Go to the website, click the button to upload your PDF, and the tool compresses it automatically. You then download the smaller file to your computer. Most online tools are free for files under 50 MB and do not require an account.

The trade-off is that your file travels to their servers and back. If the PDF contains sensitive information — medical records, tax returns, legal documents — uploading it to the internet may not be safe. Check the website's privacy policy before uploading. Some online tools delete files after a few hours; others keep them longer.

Use Adobe Acrobat Pro for the most control

Adobe Acrobat Pro (the paid version, not the free Reader) lets you compress PDFs with precise control over image quality, resolution, and which elements to compress. Open the PDF, go to File > Save As Other > Reduced Size PDF, and choose your compression level. You can also use Tools > Optimize PDF to set exact parameters for images, fonts, and metadata.

Acrobat Pro costs about $180 per year or $20 per month. It is worth the cost if you compress PDFs regularly or need to preserve specific quality levels. The free version, Adobe Reader, cannot compress files.

Use Ghostscript if you want free desktop software

Ghostscript is free, open-source software that compresses PDFs from the command line — it requires typing commands rather than clicking buttons, so it is better for people comfortable with a terminal or command prompt. Download Ghostscript from ghostscript.com, install it, then open your terminal or command prompt.

The basic command is: gswin64c -sDEVICE=pdfwrite -dCompatibilityLevel=1.4 -dPDFSETTINGS=/ebook -dNOPAUSE -dQUIET -dBATCH -sOutputFile=output.pdf input.pdf (replace input.pdf with your filename and output.pdf with what you want to call the compressed version). The -dPDFSETTINGS flag controls compression: /screen is smallest but lowest quality, /ebook is medium, /printer is high quality. This method gives you the most control but has the steepest learning curve.

Understand what compression actually does

PDF compression works by reducing the resolution and color depth of images inside the file, removing metadata (information about who created the file and when), and sometimes deleting fonts that are not needed to display text. Text itself does not compress much because it is already small; most file size comes from images.

A PDF with 50 photographs will shrink much more than a PDF with 50 pages of text and a few charts. Compressing to "low" quality can cut file size by 60 to 80 percent but makes photos look blurry. Compressing to "medium" usually cuts 30 to 50 percent and keeps images readable. If you need to send a PDF by email and it is too large, medium compression is usually the right choice.

Frequently Asked Questions

How much smaller will my PDF get after compression?

It depends on what is inside. A PDF full of high-resolution photographs might shrink by 60 to 80 percent. A PDF that is mostly text with a few small images might shrink by only 10 to 20 percent. Try compressing a copy first to see the result before you replace the original.

Will compression make my PDF look bad?

Compression always reduces image sharpness to some degree. Text stays readable at any compression level. If the PDF is mostly text with a few images, you probably will not notice a difference. If it is full of photographs or detailed graphics, the images will look softer or blurrier, especially at "low" quality settings.

Can I compress a PDF that is password-protected?

Most compression tools cannot read password-protected PDFs. You will need to remove the password first using the program that created it or a password-removal tool. Once the password is gone, you can compress normally.

Is it safe to use online PDF compression tools?

Online tools are safe for non-sensitive files like resumes, presentations, or articles. For medical records, tax returns, legal documents, or anything with personal information, use a tool on your own computer instead — Windows Print to PDF, Mac Preview, or Ghostscript all keep files offline.

What if I compress a PDF and it is still too large?

Try compressing again at a lower quality setting, or split the PDF into smaller files. If the PDF is mostly images, you could also convert it to a different format like JPG (if it is a scanned document) or use a tool that removes pages you do not need.

This guide is for general information only and is not medical, financial, legal, or other professional advice. For decisions specific to your situation, consult a qualified professional. See our Editorial Policy.