PDF GUIDE

How to reduce PDF file size without guessing

Published and reviewed by Klikivo · 21 September 2026

The best compression method depends on what makes the document large. A scanned contract, a presentation exported from design software and a text-only report need different treatment.

First identify the PDF type

Scanned document

Every page is essentially a photograph. Image resolution and JPEG quality usually dominate the file size. Rendering pages at a lower resolution can produce a large reduction, but text may no longer be selectable.

Image-heavy document

Catalogues and slide decks contain many high-resolution images. Resizing images before creating the PDF often gives a cleaner result than repeatedly recompressing the finished document.

Text-based document

A digitally generated report may already be compact. Rebuilding its pages as images can make it larger and removes searchable text, links and accessibility information. In this case, remove unused assets in the source application and export again.

Choose quality deliberately

A lower quality value does not always mean a better result. Fine print, signatures and thin lines show compression artefacts first. Start near 65–75%, inspect several pages at normal reading size and lower the setting only if the document remains legible.

Keep the original. Browser compression creates a new file. Store the source PDF separately, especially for contracts, invoices, signed records and archival documents.

Privacy and processing limits

PDFs may contain personal, financial or legal information. Klikivo's compressor performs the rendering in your browser. To prevent excessive memory use, it limits the input to 30 MB and 40 pages. Password-protected or damaged documents may not open.

When not to compress

Do not rasterize a PDF that must retain selectable text or working links.
Do not use a reduced copy as an archival master.
Do not assume a smaller file preserves digital signatures; changing document bytes normally invalidates signatures.
Do not continue if names, totals or fine print become difficult to read.

Try the appropriate workflow

Use Compress PDF for scanned or image-heavy files. If you are building a document from photos, resize them first with the image compressor, then use Images to PDF.