How much can I reduce a PDF's file size?+
PDFs containing large embedded images can be reduced by 40–80%. PDFs with mostly text and vector graphics see smaller reductions of 5–20%.
Does compression affect text quality?+
No. Text and vector graphics are unaffected. Only embedded raster images are resampled, and only when using medium or aggressive settings.
Why is my compressed PDF larger than the original?+
This can happen with already-optimised PDFs. If the original was already well-compressed, the tool adds minimal overhead. Try the 'Light' compression level.
Can I compress a password-protected PDF?+
No. Remove password protection first using the PDF Password tool, compress, then re-protect if needed.
How much compression can I realistically expect from this tool?+
PDFs heavy with embedded photos can shrink 40-80% with aggressive settings. Text-heavy PDFs with vector graphics see smaller reductions of 5-20%. A PDF already optimised at creation (e.g. exported from Adobe InDesign at press quality) will compress less than a casually generated one.
What is the difference between lossless and lossy PDF compression?+
Lossless compression (used on vector elements and text) reduces file size without any quality change. Lossy compression (applied to embedded images) resamples images at lower resolution or quality. The light setting is mostly lossless; aggressive settings apply lossy image resampling.
Can I control image quality settings during PDF compression?+
Yes. Select 'Custom' compression and adjust the image DPI (dots per inch) and JPEG quality slider. For screen use, 72-96 DPI is sufficient. For print, keep images at 150-300 DPI. Lower DPI produces smaller files at the cost of print sharpness.
What if my compressed PDF is the same size or larger than the original?+
This happens when the source PDF is already well-optimised. PDFs from Adobe Acrobat with 'Optimise PDF' applied, or PDFs with mostly vector text, have limited room for further reduction. Try the Aggressive setting - if it still cannot reduce the size, the PDF is already near-optimal.