Most PDF compressors offer quality presets with names like "Screen", "eBook", and "Print". These names come from Ghostscript, the open-source PDF tool that has been a standard part of PDF processing pipelines for decades. But what do they actually do?
Screen: maximum compression for digital sharing
The Screen preset applies very aggressive compression — typically 50–60% JPEG quality and downscaling to 72 DPI. This was originally designed for PDFs that would only ever be displayed on a monitor and never printed. The output is noticeably lower quality when zoomed in, but at normal reading zoom on a screen, text and images are typically still legible. Use Screen when you need the smallest possible file for email attachments, messaging apps, or quick digital sharing and visual quality is secondary to file size.
eBook: the everyday default
The eBook preset uses approximately 75% JPEG quality and downscales images to around 150 DPI. This is the sweet spot for most use cases: the output is significantly smaller than the original, and the quality is good enough for comfortable screen reading even when zoomed in. At normal zoom, eBook-compressed PDFs are virtually indistinguishable from the original for most document types. Use eBook for general-purpose sharing, web uploads, and any situation where you want a good balance without thinking too hard about settings.
Print: quality preservation for physical output
The Print preset targets approximately 90% JPEG quality and preserves image resolution at 300 DPI — the standard minimum for professional print quality. Files compressed with the Print preset will be substantially smaller than originals for image-heavy PDFs while retaining enough fidelity for print. Use Print when the output will be sent to a commercial printer, included in a design workflow, or archived for long-term reference.
Custom: full control
The Custom preset exposes both the JPEG quality slider and the render scale control independently. Render scale determines the resolution at which pages are rasterised before JPEG encoding. Reducing render scale has a larger impact on file size than reducing quality alone. For very aggressive compression, reduce both settings together.
