10 practical tips to optimize PDF files

Why can a PDF be large?

Images, fonts, attachments and other objects can account for different parts of a file. In a scanned document, each page may contain an image; fonts, forms or attachments can also affect size. If your PDF reader offers a space-usage audit, use it to identify large elements before making changes.

10 ways to optimize a PDF

1. Inspect what uses space. If your PDF reader provides a space-usage audit, check images, fonts, forms and attachments before deciding what to change.
2. Adjust images carefully. For raster images, reduce dimensions or resolution only for the intended use. No single DPI value suits every screen, printer, document or recipient requirement.
3. Check export settings at the source. When exporting from the original editor, choose settings that fit the destination and compare the result with the source. For an existing PDF, test a copy with the ConverteArq PDF compressor and review the output.
4. Subset fonts only when appropriate. If the editor and font license allow it, embedding only the characters used may reduce font data. Check that the document still looks correct.
5. Use OCR for scanned pages when needed. OCR can make text searchable, but it does not guarantee a smaller file. Check readability and text selection in the result; see our OCR guide.
6. Review metadata separately. Check title, author, dates and other metadata when privacy matters. Do not assume compression removes them; use a dedicated function and verify the result.
7. Use grayscale only when suitable. The file may become smaller, but confirm that charts, photos and color-coded information remain understandable.
8. Remove only pages that are truly unnecessary. Check the document and recipient requirements first. PDF page tools can create a copy containing selected pages.
9. Review embedded attachments. Remove embedded files only when they are not needed; they may be part of the document or its record.
10. Compare compression settings. Check file size and readability on a computer and phone. Keep the original until you have verified the new copy.

When not to compress

For print, follow the print shop or recipient specifications for resolution, color, fonts and PDF standard. Lossy compression can affect detail. Keep the original and check a proof before sending.

Use PDF/A only when required

PDF/A is a family of formats intended for document preservation. Use it when the recipient or an archive policy requires it; conversion can change features and file size, so check conformance and the result.

Continue with a related guide

For a practical walkthrough of reducing a PDF file size, read How to reduce a PDF file size.

Sources and documentation

• Adobe Acrobat: PDF Optimizer settings (English)
• Adobe Acrobat: settings for scanned PDFs (English)