Skip to main content

Compress PDF Advanced

A PDF compressor reduces a PDF's file size, mostly by re-encoding the images inside it. The ZTools Compress PDF tool has two modes. On our server, it re-encodes the photos and scans inside the PDF as JPEG and scales down oversized ones at a light, balanced or strong setting, while text, links and vector graphics stay as they are, so the text remains selectable and searchable; it takes PDFs up to 50 MB and 500 pages, needs a free Google sign-in, and deletes your file right after processing. On this device, nothing is uploaded: a lossless re-save gives modest savings with everything untouched, and a rasterise option turns each page into an image at the resolution you choose, which shrinks scanned PDFs a lot but makes the text unselectable.

Use cases​

Squeezing a 25 MB report under a 10 MB email attachment limit​

Outlook, Gmail, and most corporate mail servers cap attachments around 10-25 MB. Scanned reports usually shrink a lot, because they are mostly image data. Saves the awkward "I had to use WeTransfer" follow-up.

Preparing PDFs for download from a website​

A 5 MB whitepaper is slow to open on a mobile connection. Compressing its images makes the download noticeably quicker.

Archiving PDF invoices or contracts cheaply​

Scanned invoices and contracts take far less storage once their images are compressed, and with the server mode their text layer stays searchable.

Uploading PDFs to forms with strict size limits​

Government portals, school applications, and visa systems often cap uploads at 1-2 MB per file. Compress to fit and submit on the first try.

How it works​

  1. Add your PDF — Any PDF that is not password-protected. The server mode takes up to 50 MB and 500 pages.
  2. Choose where to compress — "On our server" keeps text selectable and needs a free Google sign-in. "On this device" works in your browser with no upload.
  3. Pick the strength — On our server: light, balanced or strong. On this device: a lossless re-save, or rasterising at a chosen resolution and image quality.
  4. Compress — Photos and scans are re-encoded; text becomes an image only if you pick the on-device rasterise option.
  5. Download and verify — Save the compressed PDF; open in your preferred reader to confirm legibility before sharing or archiving.

Examples​

Input: 25 MB scanned annual report (40 pages, full-color scans)

Output: Several times smaller at balanced on our server, and still easy to read on screen

Input: 5 MB text-heavy contract (20 pages, mostly text + 2 small logos)

Output: Only slightly smaller

Frequently asked questions​

How small can a PDF get?

Image-heavy PDFs (scans, brochures) often shrink a lot. Text-heavy PDFs shrink little because text is already compact. The actual ratio depends on what's inside the file.

Will compression hurt my PDF's quality?

It depends on the strength. Strong is fine for on-screen reading but may look soft when printed; light keeps near-original sharpness. Always check the result before sharing.

Will my PDF be uploaded?

Only in the "On our server" mode, which sends it over HTTPS to our own processing server; the server deletes the PDF and the result right after processing. The "On this device" mode never uploads anything.

Does the tool work on text-only PDFs?

Yes, but savings are modest because text is already compactly stored. The biggest savings come from PDFs containing embedded images, especially high-resolution scans.

Is OCR (text extraction from scans) preserved?

On our server, yes — only the images are re-encoded, so an existing text layer stays searchable. The on-device rasterise option turns pages into images and removes it.

Can I compress an encrypted/password-protected PDF?

Unlock it first using our PDF Unlock tool (you must know the password). Compressing an encrypted PDF directly will fail.

Tips​

  • Try balanced first — it is the best trade-off for most PDFs.
  • For archival storage, strong is fine when the file only needs to be read on screen.
  • For documents that will be printed, stay on light.
  • Combine with PDF Splitter when each part needs to fit a separate size limit.

Try it now​

The full Compress PDF Advanced runs at https://ztools.zaions.com/compress-pdf-advanced. It can process your file on the ZTools server: the file is uploaded temporarily and deleted right after processing, and that mode needs a Google sign-in.

Open the tool ↗

Last updated: 2026-09-11 · Author: Ahsan Mahmood · Edit this page on GitHub