The fastest way to shrink a PDF depends on what's inside it
A PDF file gets large because it contains images, fonts, or both at high resolution. To make it smaller, you remove resolution you probably don't need — a document you're emailing doesn't need the same image quality as one you're printing on a professional printer. The method you use depends on whether you're working on Windows, Mac, or just have a web browser.
Most PDFs shrink by 30 to 60 percent when you compress the images inside them. Some shrink more if they contain scanned pages or photographs. The trade-off is that the images will look slightly softer on screen, though text usually stays sharp because PDFs store text separately from images.
Key Takeaways
- Online PDF compressors like Smallpdf or ILovePDF work in any web browser and require no software installation.
- Windows users can right-click a PDF, choose "Print," select "Microsoft Print to PDF," and change the quality setting to reduce file size.
- Mac users can open a PDF in Preview, go to File > Export, and choose "Quartz Filter" set to "Reduce File Size."
- Compressing a PDF usually makes images softer but keeps text sharp, and most files shrink 30 to 60 percent.
Using an online PDF compressor in your web browser
Online compressors work on any device with a browser and require no software download. Smallpdf and ILovePDF are the most common. Both let you upload a PDF, compress it, and download the result in seconds. Neither requires you to create an account, though both offer paid plans with extra features.
Go to Smallpdf.com or ILovePDF.com, click the "Compress PDF" button, and drag your file into the box or click to select it from your computer. The site will process it and show you the new file size. Download the compressed file to your computer. The original stays on your computer unchanged.
The main drawback is that you're uploading your file to someone else's server. If the PDF contains sensitive information, this method may not be right for you. Both sites say they delete files after an hour, but read their privacy policy if you're uncertain.
Compressing a PDF on Windows using Print to PDF
Windows has a built-in tool that can compress PDFs without any extra software. Right-click the PDF file, select "Open with," and choose "Microsoft Edge" or another browser. Once the PDF is open, press Ctrl+P to open the Print dialog.
In the Print dialog, look for "Printer" at the top and click the dropdown. Select "Microsoft Print to PDF." Below that, look for "More settings" or a similar option and click it. Find the setting labeled "Quality" or "Print quality" and change it from "High" or "Best" to "Medium" or "Standard." Then click "Print" and choose where to save the new file.
This method works well for documents with images or scanned pages. Text-heavy PDFs may not shrink much because the text is already compressed. The new file will have noticeably softer images, but the text will remain readable.
Compressing a PDF on Mac using Preview
Mac's built-in Preview app can compress PDFs without installing anything. Right-click the PDF file, select "Open With," and choose "Preview." Once the file opens, click "File" in the menu bar and select "Export."
In the Export window, make sure the file format is set to "PDF." Below that, look for "Quartz Filter" and click the dropdown. Select "Reduce File Size." Then click "Save" and choose where to store the compressed file.
This method is straightforward and usually reduces file size by 40 to 50 percent on documents with images. The quality loss is similar to the Windows method — images become softer but text stays sharp.
When compression doesn't shrink the file much
Some PDFs don't shrink much no matter which method you use. This usually means the file is mostly text with few or no images, or the images are already compressed. PDFs created from text documents (like a Word file converted to PDF) often fall into this category.
If you're trying to email a text-heavy PDF and it's still too large, the problem may not be compression. Check whether you can remove pages you don't need, delete attachments embedded in the PDF, or split it into multiple smaller files. Some online tools let you do this without downloading software.
Comparing your options
| Method | Works on | Setup time | File size reduction | Best for |
|---|---|---|---|---|
| Online compressor (Smallpdf, ILovePDF) | Any device with a browser | None | 30–60% | Quick compression, any file type |
| Windows Print to PDF | Windows only | None | 30–50% | PDFs with images or scans |
| Mac Preview | Mac only | None | 40–50% | PDFs with images or scans |
Frequently Asked Questions
Will compressing a PDF make it unreadable?
No. Compression reduces image quality, not readability. Text stays sharp because PDFs store text separately from images. The file will look slightly softer on screen, but you'll still be able to read everything.
Can I compress a PDF multiple times to make it even smaller?
You can, but the benefit drops sharply after the first compression. Compressing twice might save another 5 to 10 percent, but the image quality will suffer noticeably. One compression is usually enough.
What if I need to send a PDF that's still too large after compression?
Try splitting the PDF into separate files using an online tool like Smallpdf's "Split PDF" feature, or remove pages you don't need. You can also ask the recipient whether they can receive files through a cloud service like Google Drive or Dropbox instead of email.
Do I need to pay for an online PDF compressor?
No. Smallpdf, ILovePDF, and most other online compressors work without payment. Paid plans add features like batch processing or removing ads, but basic compression is free.
Is it safe to upload my PDF to an online compressor?
Most reputable compressors delete files after one hour and use encryption during upload. If your PDF contains sensitive information, use the Windows Print to PDF or Mac Preview method instead, which keeps everything on your computer.