How to Compress a PDF

PDF files can grow large surprisingly fast — a report with embedded photos, a scanned contract, or a Canva export can easily top 10 MB. Compressing a PDF reduces that size so it is easier to email, upload to a web form, or share over a messaging app, without affecting the text, hyperlinks, or vector graphics inside.

Why PDFs Get Large

Most PDF bloat comes from embedded images. When you export a document from a design tool or scan a paper document, images are stored as raw JPEG or PNG data inside the file. A single high-resolution photo can add several megabytes on its own. Text and vector graphics, by contrast, are already compact — PDF stores them as mathematical descriptions rather than pixels.

• Scanned documents: each page is a full-resolution photo, often 200–300 dpi at A4 or Letter size.
• Presentation exports: slides from PowerPoint or Canva embed images at high pixel counts.
• Reports with photos: product catalogues, marketing decks, and annual reports typically embed many high-res images.
• PDF/A archives: archival PDFs embed all fonts as subsets, adding overhead even without images.

What Compression Actually Does

A PDF compressor that preserves quality works at the image level, not the page level. It extracts each embedded JPEG image, re-encodes it at a lower quality setting (which removes high-frequency detail invisible at normal reading distances), optionally scales it down if it is far larger than the target DPI, and puts the smaller version back. The result is a structurally identical PDF where text is still selectable, links still work, and fonts are still embedded — only the image data has changed.

Avoid tools that "compress" by rasterizing every page to an image. That approach does reduce file size, but it destroys text searchability, breaks copy-paste, and makes the PDF look blurry when zoomed in. A good compressor never converts a page to a bitmap.

How to Compress a PDF — Step by Step

1. 1

   Open the Compress PDF tool

   Go to the Compress PDF tool on WeConvertIt. It runs entirely in your browser — no sign-up and no file upload required.

2. 2

   Drop or select your PDF

   Drag your PDF onto the drop zone, or click to browse for it. The tool reads the file locally — nothing is sent to a server.

3. 3

   Choose a compression level

   Pick Light (85% quality, 2400 px cap) for near-original fidelity, Balanced (75%, 1800 px) for the best size-to-quality trade-off, or Maximum (60%, 1200 px) for the smallest possible file.

4. 4

   Click "Compress PDF"

   The tool scans the file for embedded JPEG images, recompresses each one, and rebuilds the document. Text, fonts, and vector graphics are completely untouched.

5. 5

   Review and download

   The result shows the before and after file sizes, the percentage saved, and how many images were recompressed. Click Download to save the compressed file.

What to Expect from the Results

Image-heavy PDFs — scanned documents, photo books, Canva exports — typically shrink 30–70% under the Balanced preset. PDFs that are mostly text and vector diagrams will see little reduction because those elements are already compact and are left untouched. The tool reports how many embedded images were found and how many were recompressed, so you can see at a glance why a file did or did not shrink.