Email Attachments

Recommended size: Under 5 MB

Many email providers limit attachment sizes to 10-25 MB. For reliable delivery, aim to keep PDF attachments under 5 MB, especially when sending to multiple recipients or to recipients who may be using mobile devices.

Optimization tips:

• Use 'Screen' or 'eBook' compression settings
• Remove unnecessary images or compress existing ones
• Consider linking to the document instead for files over 20 MB

Website Downloads

Recommended size: Under 3 MB

PDFs hosted on websites should be as small as possible to reduce load times and bandwidth usage, especially for users on mobile connections.

Optimization tips:

• Use 'Screen' compression setting for primarily text documents
• Optimize images to 72-96 DPI
• Remove embedded fonts when possible

Printing & Professional Distribution

Recommended size: 5-15 MB (depends on page count and image quality needs)

Documents intended for high-quality printing or professional distribution need to balance quality with practicality.

Optimization tips:

• Use 'Printer' or 'Prepress' compression settings
• Maintain image resolution of 300 DPI for printing
• Include necessary fonts but remove unnecessary metadata

Archiving & Long-term Storage

Recommended size: Balance between quality and size

Archived documents should maintain enough quality to be useful in the future while not consuming excessive storage space.

Optimization tips:

• Use 'Printer' compression for most documents
• Consider PDF/A format for long-term archival needs
• Embed necessary fonts for future compatibility

Images

Images typically account for the largest portion of a PDF's file size. The resolution, type, and number of images dramatically impact the overall size.

Size reduction tips:

• Reduce image resolution to the minimum needed for your purpose
• Convert color images to grayscale when color isn't necessary
• Use JPEG compression for photographs
• Use PNG compression for diagrams or text-based images

Fonts

Embedded fonts ensure your document looks the same on any device but add to the file size.

Size reduction tips:

• Use common fonts when possible
• Subset fonts to include only the characters used
• Limit the number of different fonts used in a document

Interactive Elements

Forms, JavaScript, videos, and other interactive elements can significantly increase file size.

Size reduction tips:

• Remove unnecessary JavaScript
• Link to external videos rather than embedding them
• Simplify form elements

Metadata & Hidden Content

PDFs can contain hidden layers, comments, annotations, and metadata that add to file size.

Size reduction tips:

• Remove document history and metadata
• Delete unused layers
• Remove comments and annotations before final distribution

Compression Levels Explained

• Screen (Level 5): Highest compression, optimized for screen viewing. Significantly reduces image quality and resolution. Best for documents that will only be viewed on screens and where file size is critical.
• eBook (Level 4): High compression with better image quality than Screen. Good balance for reading on tablets and e-readers.
• Printer (Level 3): Medium compression suitable for standard office printing. Maintains reasonable image quality while reducing file size.
• Prepress (Level 2): Light compression designed for high-quality printing. Preserves most image details.
• Default (Level 1): Minimal compression that preserves maximum quality. Use when quality is more important than file size.

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