Sejda PDF

Compress PDF

Make a heavy PDF small enough to email.

Drag & drop a PDF here

One file at a time, up to 100 MB

Compression happens entirely in your browser - your file never leaves this device.

About Compress PDF

Images are resampled, duplicate resources are merged and unused objects are dropped. Pick a quality level and see the resulting size before you commit to the download.

  • Typically 40-80% smaller
  • Text stays sharp and selectable
  • Optional target size

How to compress pdf

  1. 1

    Upload the file

    Scans and image-heavy decks shrink the most.

  2. 2

    Choose a level

    Light, recommended or strong compression.

  3. 3

    Compare and download

    Before and after sizes are shown side by side.

A practical guide to compress pdf

Why text barely shrinks but scans collapse

The single most useful thing to understand about compression is where the weight lives. Text and vector graphics are stored as compact instructions, effectively drawn on demand, so they are already tiny and there is little to squeeze. Images are stored as pixels, and pixels are heavy, so a scanned page or a photo-rich report is almost entirely image data. Compression works by resampling those images to a sensible resolution and re-encoding them efficiently, then discarding duplicate and unused objects. That is why a 40-page contract of pure text hardly changes while a 5-page scan can shrink by most of its size.

Picking a level for the job

Match the setting to how the file will be used. Light compression keeps images crisp and suits documents that may be printed or archived, where a modest size cut is enough. The recommended level is the everyday choice for emailing and sharing, balancing quality against size. Strong compression goes furthest for uploads with tight limits or screen-only viewing, at the cost of some image sharpness. Because the tool shows the before and after sizes side by side, you can start at recommended, check the preview, and only reach for strong if you still need to shave more off.

Compressing as part of a larger workflow

Compression usually pairs well with other steps rather than standing alone. If a file is heavy because it is a stack of full-resolution photos, converting them thoughtfully or cropping away wasted margins first gives compression less to fight. When a document is too big for an email limit even after compressing, splitting it into smaller parts is the reliable fallback. And if you are compressing to send a scan, run OCR before compression, not after, so recognition works on the sharper original images and you still get a searchable, lightweight file at the end.

Frequently asked questions

Which files shrink the most?
Scans, photo-heavy brochures and image-laden slide decks shrink the most, often dramatically, because their bulk is images that can be resampled. A document that is mostly typed text is already compact, so expect only a small reduction from tidying up unused objects.
Will compressing again make the file even smaller?
Barely, and it is not worth it. Once the images have been resampled the easy savings are gone, and running it repeatedly mostly re-encodes already-reduced images, which can soften them further for little size benefit. Compress once at the right level instead.
Does compression remove text, bookmarks or form fields?
No. It targets images and redundant internal data, leaving your text, links, bookmarks and form fields intact. The document reads and behaves the same; it just carries less weight.
The images look softer after strong compression. Can I dial that back?
Yes. Strong compression resamples images most aggressively to hit the smallest size. Drop to the recommended or light level, or set a target size, and the tool preserves more image detail while still trimming the file.

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