The quickest way to shrink a PDF

The fastest method depends on what device you're using. On Windows, macOS, or Linux, you can use a free online tool like Smallpdf or ILovePDF — upload your PDF, choose compression, and download the result in seconds. On any device with a web browser, this takes about two minutes total. If you want to keep the file on your computer without uploading it anywhere, most operating systems have built-in tools: macOS has Preview, Windows 10 and 11 have the Print to PDF feature, and Linux users typically have access to command-line tools like GhostScript.

The trade-off is always the same: smaller file size means lower image quality. A PDF shrunk to 1 MB will look noticeably grainier than the original if it contains photos or scans. A document with mostly text survives compression much better. Before you compress, think about what the file will be used for — if you're emailing it to someone who needs to read text, aggressive compression is fine. If someone needs to print it or zoom in on images, you want less compression.

Key Takeaways

  • Online tools like Smallpdf and ILovePDF compress PDFs in your browser without installing software, though they require uploading your file to their servers.
  • macOS Preview and Windows Print to PDF are built-in options that keep your file on your computer but require a few extra steps.
  • Compression always trades file size for image quality — text documents compress well, but PDFs with photos will look grainier at smaller sizes.
  • Most PDFs can be reduced to 30 to 50 percent of their original size without becoming unreadable, depending on their content.

Using online compression tools

Online tools are the simplest route if you don't mind uploading your PDF temporarily. Go to Smallpdf.com, ILovePDF.com, or Compresser.io, click the upload button, select your PDF, and the tool automatically compresses it. You then download the result. Most of these sites let you adjust the compression level — "low" keeps more detail, "high" makes the file much smaller. Start with medium compression and download to see if the quality is acceptable.

The main drawback is privacy: your PDF sits on someone else's server while it's being processed. Most reputable tools delete files after a few hours, but if your PDF contains sensitive information — medical records, financial statements, or personal details — you may not want to upload it. Check the tool's privacy policy before you use it. Smallpdf and ILovePDF both state they delete files automatically, but read their terms if you're uncertain.

These tools usually work on any device with a web browser, including phones and tablets, so you don't need to own a specific operating system or install anything.

Compressing on macOS using Preview

Open your PDF in Preview (the default PDF reader on macOS). Go to the File menu, click Export, and a dialog box appears. At the bottom, you'll see a dropdown that says "PDF" — leave it there. Below that is a "Quartz Filter" dropdown; click it and select "Reduce File Size." Then choose where to save the file and click Save.

Preview's compression is moderate — it typically reduces file size by 30 to 50 percent without making text unreadable, though images will lose some sharpness. If the result is still too large, you can repeat the process on the already-compressed file, but quality drops further each time. For most documents, one pass through Reduce File Size is enough.

Compressing on Windows using Print to PDF

Open your PDF in any program that can read it — Adobe Reader, Microsoft Edge, or even Chrome all work. Go to File and click Print. In the printer dropdown, select "Print to PDF" or "Microsoft Print to PDF" (the exact name depends on your Windows version). Before you click Print, look for a "Properties" or "Preferences" button and check for compression or quality settings — some versions let you choose "Draft" or "Low Quality" to shrink the file further.

Click Print, choose where to save the new file, and Windows creates a compressed copy. This method usually reduces file size by 20 to 40 percent. The quality loss is similar to Preview on macOS — text stays readable, but images become noticeably softer.

Using GhostScript on Linux

If you use Linux and want to avoid uploading files, GhostScript is a command-line tool that compresses PDFs. Open a terminal and run this command, replacing "input.pdf" with your file's name and "output.pdf" with what you want to call the compressed version:

gs -sDEVICE=pdfwrite -dCompatibilityLevel=1.4 -dPDFSETTINGS=/ebook -dNOPAUSE -dQUIET -dBATCH -sOutputFile=output.pdf input.pdf

The "-dPDFSETTINGS=/ebook" setting provides moderate compression. Replace "ebook" with "screen" for more aggressive compression (smaller file, lower quality) or "prepress" for less compression (larger file, better quality). GhostScript is often pre-installed on Linux systems, but if you get a "command not found" error, install it through your package manager — on Ubuntu or Debian, run sudo apt install ghostscript.

When compression isn't enough

Some PDFs stay large even after compression because they contain embedded fonts, high-resolution images, or multiple pages. If you've compressed once and the file is still too big, you have a few options. You can split the PDF into smaller chunks — many online tools and desktop programs let you extract specific pages and save them as separate files. This works well if you only need to send certain pages to someone.

You can also convert the PDF to an image format like JPG or PNG, which compresses much more aggressively, though you lose the ability to select and copy text. Some online tools offer this conversion. Finally, if the PDF contains mostly scanned images of documents, you could run it through optical character recognition (OCR) software, which converts images of text into actual text — the resulting file is much smaller because text takes up far less space than images. Free OCR tools like Tesseract exist, but they require some technical knowledge to use.

Frequently Asked Questions

Is it safe to use online PDF compression tools?

Reputable tools like Smallpdf and ILovePDF are generally safe — they use encryption and delete files automatically after a few hours. However, your PDF does travel to their servers, so avoid uploading files with highly sensitive information like passwords or social security numbers. If you're uncertain, use a built-in tool on your computer instead.

Will compressing a PDF make it unreadable?

No. Compression reduces image quality and file size, but text remains readable at normal compression levels. You only run into readability problems if you compress extremely aggressively multiple times in a row. Start with medium compression and check the result before deciding to compress further.

Can I compress a PDF that's password-protected?

Most online tools and built-in compression features cannot process password-protected PDFs — you'll need to remove the password first. If you own the PDF, you can usually do this in Adobe Reader or Preview by opening the file, going to File or Tools, and looking for a "Remove Security" or "Remove Password" option. If you don't know the password, you cannot legally remove it.

How much smaller will my PDF get after compression?

It depends on what's in the file. Text-heavy PDFs typically shrink to 50 to 70 percent of their original size. PDFs with many photos or scans can shrink to 20 to 40 percent of the original, though image quality drops noticeably. The only way to know for your specific file is to try compressing it and checking the result.

What's the difference between the compression options on online tools?

"Low" compression removes very little data, so the file stays large but looks nearly identical to the original. "Medium" removes some image detail and is suitable for most uses. "High" or "maximum" compression makes the file as small as possible but images look grainy. For emailing or sharing, medium is usually the right choice.