How to Reduce PDF File Size
To reduce PDF file size, compress the images inside it and rebuild the file structure. The free PDF compressor on PDFDEN does both in your browser and shows the size before and after. Text and vector graphics stay sharp at every level.
Compress PDF: Make a PDF smaller for email or upload. Free, and your file never leaves your device.
Open Compress PDFSteps
Open Compress PDF and drop in your PDF. You can add several files at once.
Choose a level. Lossless keeps every image as it is. Balanced re-encodes large photos as JPEG and scales them to about 2000 px on the long side. Strong goes to about 1400 px.
Run the compression and check the before and after size shown for each file.
Download the smaller PDF. If a result came out bigger, PDFDEN keeps your original instead.
Which compression level to pick
Start with Balanced. Most large PDFs are large because of photos or scans, and this level cuts those down while keeping them clear on screen and in print.
Use Lossless when images must stay pixel-perfect, like technical drawings or a portfolio. It saves less, but nothing visible changes.
Pick Strong when the file has to fit a hard limit, such as an email attachment cap or an upload form. Photos lose some detail. Text is never turned into an image, so it stays crisp and searchable.
Other ways to make a PDF smaller
Compression is not the only lever. Removing content often saves more:
- Cut pages nobody needs with Delete PDF Pages. Our guide on how to delete pages from a PDF covers it step by step.
- Scanned documents often carry empty pages. Remove Blank Pages finds and drops them.
After that, run the file through the PDF size reducer again. The savings stack.
Compress PDF: Make a PDF smaller for email or upload. Free, and your file never leaves your device.
Open Compress PDFHow to reduce PDF size on a Mac with Preview
Preview has a built-in filter. Open the PDF, choose File > Export, set Quartz Filter to Reduce File Size and save. It works, but it is blunt: it can shrink images so hard that scans turn blurry, and there is no setting in between.
Windows has no built-in PDF compressor. Printing to "Microsoft Print to PDF" rarely makes a file smaller and can drop links. A browser tool with adjustable levels gives you more control on either system.
Why some PDFs barely shrink
A PDF that is mostly text is already small, so there is little to gain. The same goes for files that were compressed before. PDFDEN checks the result and keeps your original if the new file is not smaller.
If a scanned PDF still feels heavy, try Grayscale PDF. It rebuilds every page as a grayscale image, which can help color scans. Text on those pages is no longer selectable afterward, so skip it for documents people need to search.
How to reduce PDF file size for email and upload forms
Email services commonly cap attachments at around 20 to 25 MB, and upload forms for jobs, visas or schools often allow far less. Check the exact limit first, then work toward it.
Run Balanced and look at the new size. Still too big? Try Strong. If even that is not enough, the file probably has more pages or images than it needs. Split it into parts with Split PDF and send them separately, or cut the extra pages.
Compress several PDFs in one go by dropping them all into the PDF compression tool together. Each file gets its own before and after size.