How to Compress a PDF Without Losing Quality (2026 Methods)

Your bank wants the loan document. Your university wants the assignment. Your client wants the proposal. All have an upload limit of 5 MB. Your PDF is 23 MB. You've been here.

Compressing a PDF can shrink it 50-90% with almost no visible quality drop — if you know what's making it big in the first place. This guide explains the why, gives you four methods, and tells you which one fits your situation.

What's actually making your PDF huge? #

Before compressing, it helps to know what's inside. PDFs are containers — they can hold text, images, fonts, embedded files, scanned pages, and metadata. Almost always, it's images that bloat the file.

Common causes by file type:

Source	Why it's big
Scanned document	Each page is a 300 DPI image, often uncompressed
PowerPoint export	Embedded images at original phone-camera resolution
Phone "Scan to PDF"	Multi-megapixel photos for each page
Word doc with images	Same — images embedded at full resolution
Plain text PDF	Should be tiny (<500 KB). If huge, it's bloated metadata

If your PDF is mostly text and still 20 MB, something weird is going on — usually duplicated fonts or hidden embedded files.

Method 1: Online (recommended for most) #

Fastest method. No software install. Works on phone, laptop, anything.

Steps #

1. Open the PDF compressor
2. Drag your PDF in (or click to browse)
3. Pick a compression level:
   • Light — best quality, 30-40% smaller
   • Medium — balanced (recommended), 50-70% smaller
   • Strong — smallest size, 70-90% smaller, slight visible drop
4. Click Compress
5. Download the result

When this is the best choice #

• Files under 100 MB
• Occasional use
• You want it done in 30 seconds

Privacy note: Files are processed on our servers and auto-deleted within 2 hours. We never read, store, or share contents.

Method 2: Adobe Acrobat (Pro) #

If you already pay for Acrobat Pro, it has solid compression built in.

Steps #

1. Open the PDF in Acrobat Pro
2. File → Save As Other → Reduced Size PDF
3. Pick a compatibility level (Acrobat 10 or newer for best compression)
4. Save

Acrobat usually gives 30-50% size reduction. Not as aggressive as dedicated compressors, but reliable and built-in.

Acrobat doesn't have a free version that does compression — the free Reader only views PDFs.

Method 3: Mac Preview (free, built-in) #

Mac users have a basic compressor baked into the default Preview app.

Steps #

1. Open the PDF in Preview
2. File → Export…
3. In the Quartz Filter dropdown, pick Reduce File Size
4. Save

The result is often too compressed for documents you'd send professionally — Preview's filter is heavy-handed. Good enough for "I need this under 5 MB and nobody's reading the fine print."

Custom Quartz filter (better quality) #

Out of the box, Preview's filter sets image quality very low. You can build a custom filter that compresses less aggressively — but this requires editing a system XML file. For most people, an online tool gives better results faster.

Method 4: Command line (Ghostscript) #

For developers and power users with big batches.

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

The -dPDFSETTINGS flag controls the trade-off:

Setting	Use case	Typical reduction
/screen	Web viewing, low DPI	80-90%
/ebook	Reading on devices	60-75%
/printer	High-quality print	30-50%
/prepress	Pro print (CMYK)	10-25%

Ghostscript is what most online compressors (including ours) run under the hood — it's the open-source standard.

To process a whole folder:

for f in *.pdf; do
  gs -sDEVICE=pdfwrite -dCompatibilityLevel=1.4 \
     -dPDFSETTINGS=/ebook -dNOPAUSE -dQUIET -dBATCH \
     -sOutputFile="compressed_$f" "$f"
done

How to compress without losing readability #

Most "compressed PDF looks bad" complaints come from one mistake: using max compression on a document that has fine details. A few rules:

For text-heavy documents (resumes, reports, contracts) #

Use Light or Medium compression. Text stays sharp; you'll save 30-60%.

For scanned documents #

Use Medium compression with OCR (if your tool supports it). Strong compression turns scanned text fuzzy.

For image-heavy documents (portfolios, brochures) #

Use Medium compression. Strong compression introduces visible JPEG artifacts in the images.

For pure text PDFs #

Compression often doesn't help much (text is already small). If your text-only PDF is huge, something else is the problem — try our PDF repair tool or strip embedded fonts.

Comparing the four methods #

Same 23 MB scanned document, results:

Method	Output Size	Quality	Time
Online (Light)	14 MB	★★★★★	12 sec
Online (Medium)	5.8 MB	★★★★	14 sec
Online (Strong)	2.1 MB	★★★	16 sec
Acrobat (Reduced Size)	11 MB	★★★★	8 sec
Mac Preview (default)	1.4 MB	★★	6 sec
Ghostscript /ebook	4.9 MB	★★★★	9 sec

The online tool's Medium setting hits the sweet spot for most situations.

What about reducing pages? #

If your PDF has pages you don't need, the fastest compression is to delete them:

• Split a PDF — extract just the pages you need
• Merge PDFs — combine multiple smaller files into one

A 50-page document split to just the 10 pages you actually need is a 5× compression for free.

Quick FAQ #

Will compressing my PDF break OCR / text search? #

No — modern compressors keep the text layer intact even when shrinking the image layer. Search still works.

Can I compress a password-protected PDF? #

You'll need the password first. Compress, then re-add the password. Online tools can't bypass PDF passwords (and shouldn't).

Does compression remove signatures? #

A digitally-signed PDF will invalidate the signature if you modify the file in any way, including compression. Compress before signing, or re-sign after compressing.

How small can a PDF actually get? #

Depends on content. A pure-text 50-page PDF can go from 4 MB to 200 KB. A 50-page image-heavy PDF might only go from 50 MB to 10 MB. Text compresses extremely well; images have a floor based on resolution and quality.

Is online compression safe for confidential documents? #

Reputable services delete uploads after a short window (we delete within 2 hours, never read contents). For extremely sensitive documents (legal, medical, financial), use the desktop Ghostscript method to keep files on your machine.

Wrapping up #

Most "I need this PDF smaller" situations are solved by Medium online compression in under 30 seconds. For batch jobs or sensitive files, the command-line route gives you full control.

Compress your first PDF free, no signup: PDF Compressor →

Need to handle PDF differently? We also have merge, split, and conversion between PDF and Word and other formats.