The fastest way to shrink a PDF
The simplest method is to re-save your PDF through your web browser or a free online tool. Open the PDF in Chrome, Firefox, or Edge, then print it to PDF with lower quality settings — this removes unnecessary data that scanners and some programs add automatically. Choose "Standard" or "Medium" quality instead of "High" when the print dialog appears, then save the new file.
If you have the original document (a Word file, image, or spreadsheet), recreate the PDF from that source instead of compressing a PDF made from a PDF. Each conversion adds file bloat, and starting fresh cuts size by 30 to 50 percent in most cases.
For a one-time job with a single file, this approach takes five minutes and costs nothing. For regular work or batches of files, the methods below give you more control.
Key Takeaways
- Printing to PDF through your browser with "Standard" quality settings removes scanner artifacts and embedded fonts that bloat file size.
- Reducing image resolution from 300 DPI to 150 DPI cuts file size in half for scanned documents without visible loss on screen or in email.
- Removing embedded fonts, metadata, and unused objects can shrink a PDF by 20 to 40 percent if the file contains unnecessary data.
- Free tools like Ghostscript, ILovePDF, and Smallpdf handle batch jobs and offer more options than browser printing, though they require uploading files to a website.
- PDFs made from images (scanned pages) compress much more than PDFs made from text, because images contain far more data.
Reducing image resolution for scanned documents
Scanned PDFs are almost always larger than they need to be because scanners default to 300 DPI (dots per inch), a resolution meant for printing on paper. For documents you will read on screen or email to someone, 150 DPI is visually identical and cuts file size roughly in half.
To change resolution, you need software that reads and rewrites the PDF. Ghostscript is free and runs on Windows, Mac, and Linux — it works from the command line, which sounds technical but requires only copying and pasting a single line of text. The command looks like this:
gs -sDEVICE=pdfwrite -dCompatibilityLevel=1.4 -dPDFSETTINGS=/ebook -r150 -o output.pdf input.pdf
Replace "input.pdf" with your file name and "output.pdf" with what you want to call the new file. The "-r150" sets resolution to 150 DPI. Change it to "-r100" for even smaller files if the document is text-heavy, or "-r200" if you need sharper images. Run the command and Ghostscript creates a new PDF in the same folder.
If command-line tools feel unfamiliar, ILovePDF and Smallpdf offer the same compression through a web browser — upload your file, choose "compress", and read the result. Both are free for one or two files per day. File size typically drops 40 to 60 percent for scanned documents.
Removing fonts and metadata that add bulk
PDFs sometimes embed entire font files inside the document so the file looks the same on any computer. For most purposes, this is unnecessary — the reader's system has common fonts already. Removing embedded fonts can shrink a file by 10 to 30 percent depending on how many fonts the PDF contains.
Adobe Acrobat Pro (the paid version, not the free Reader) can remove embedded fonts through File > Properties > Fonts, then uncheck "Embed" for each font. This requires owning Acrobat, which costs money and is overkill for occasional use.
For free removal, Ghostscript handles this too. Use the command above but add "-dSubsetFonts=true" to the line — Ghostscript will subset fonts (keep only the characters actually used) rather than embed entire font files. Metadata — invisible information like creation date, author name, and editing history — also adds kilobytes. Most free tools strip this automatically when you compress.
Comparing free tools for different situations
| Tool | Best for | How it works | File limit |
|---|---|---|---|
| Browser print-to-PDF | Single files, no setup | Open PDF, print, choose "Standard" quality | One file at a time |
| ILovePDF or Smallpdf | Scanned documents, quick jobs | Upload file, click compress, read | 1–2 files per day free |
| Ghostscript | Batch jobs, full control | Run command in terminal | Unlimited |
| Adobe Acrobat Pro | Regular professional work | File menu, built-in compression | Unlimited (paid software) |
Why some PDFs compress more than others
A PDF made from scanned images compresses far more than a PDF made from text because images contain vastly more data. A 50-page scanned document at 300 DPI might be 100 MB; the same document as text (created by OCR or typed originally) might be 2 MB. Compression can shrink the scanned version to 20 MB, but the text version barely shrinks because there is little fat to remove.
PDFs with embedded videos, high-resolution photos, or multiple fonts also compress less than straightforward text documents. If your PDF is already small (under 5 MB), compression may only save a few hundred kilobytes — not worth the effort. If it is 20 MB or larger, compression usually saves several megabytes.
Check your file size by right-clicking the PDF on Windows (Properties) or Mac (Get Info). If it is under 10 MB and you are only emailing it once, the time to compress may not be worth the savings.
When to use each compression level
Screen viewing only (email, shared drives, reading on a monitor): Use 100 to 150 DPI resolution. Quality loss is invisible on screen, and file size drops 50 to 70 percent. This is safe for almost all documents.
Printing at home or office: Use 150 to 200 DPI. The document will print clearly on standard paper, and you still save 30 to 50 percent compared to the original. Avoid going below 150 DPI if printing is a possibility.
Professional printing or archival: Do not compress. Keep the original 300 DPI file. Printers and archives need the full resolution, and compression may introduce artifacts (small visual errors) that matter at large sizes.
Text-only documents (no images or scans): Compression saves very little. Focus instead on removing embedded fonts and metadata, which might save 10 to 20 percent. The effort is usually not worth it.
Preventing large PDFs in the first place
The easiest way to manage PDF size is to avoid creating oversized files. When scanning documents, choose 150 DPI from the start if you will only view them on screen. When exporting from Word, Excel, or design software, use "Standard" quality rather than "High" — the difference is invisible for most documents.
If you regularly work with scanned documents, configure your scanner's default settings to 150 DPI and black-and-white mode (if color is not needed). This cuts file size at the source and saves compression work later.
When receiving large PDFs from others, ask whether they have a lower-resolution version. Many organizations keep both a high-quality archive copy and a smaller version for sharing — you may not need to compress at all.
Frequently Asked Questions
Will compressing a PDF make it blurry or hard to read?
Not if you compress for the right purpose. Reducing resolution from 300 to 150 DPI is invisible on screen and in email. If you print the document, text stays sharp but fine images may look slightly softer. Going below 100 DPI makes text noticeably fuzzy. Choose your resolution based on how you will use the file.
Can I compress a PDF that is already been compressed?
Yes, but with diminishing returns. Compressing an already-compressed file saves only 5 to 15 percent more because most removable data is gone. If you need smaller files, recreate the PDF from the original source document instead of compressing a PDF made from a PDF.
What is the smallest file size I can get?
For a scanned 50-page document, expect 10 to 20 MB after compression (from 50 to 100 MB originally). For a text-only PDF, expect 1 to 5 MB. The smallest possible size depends on content — images compress less than text, and color compresses less than black-and-white.
Do I need special software to compress PDFs?
No. Your web browser can do it (print to PDF with lower quality), and free online tools like ILovePDF work in any browser. Ghostscript is free but requires typing a command. You only need paid software like Adobe Acrobat Pro if you compress files constantly and want a graphical interface.
Will compressed PDFs work on all devices and email services?
Yes. Compressed PDFs are still standard PDF files — they open in any PDF reader on any device. Email services accept them the same way they accept uncompressed PDFs. The only difference is file size.