PDF Optimization Guide

Authoritative PDF optimization guide covering compression levels, DPI trade-offs, font subsetting, and portal checklists.

PDF Optimization Guide

Use RatPDF's free PDF compressor — Ghostscript-powered, no signup required.

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Searching for pdf optimization guide? Quality and file size pull in opposite directions — the art is finding the minimum compression that still looks professional. RatPDF exposes three explicit levels so you control that trade-off.

Understanding compression levels

Level	Best for	Typical reduction
Less (lossless-leaning)	Text contracts, vector diagrams	5–20%
Recommended (/ebook)	Mixed text + images, résumés	30–60%
Extreme (/screen)	Scans, photos, strict KB limits	60–90%

What stays sharp?

Vector text and line art survive all levels because they are not re-rasterized. Embedded JPEG photos absorb most of the byte loss. If your PDF is scan-only (each page is one big image), expect visible softness at Extreme — that is the physics of lower DPI.

Lossless vs lossy in practice

True lossless PDF compression removes redundancy but cannot magically shrink a 5 MB photo scan. Lossy re-encoding is required for order-of-magnitude gains. For archival legal records, keep an uncompressed original and distribute a compressed copy.

Web optimization

PDFs embedded in websites should load under 1 MB when possible. Combine compression with Flatten PDF to remove interactive form overhead if users only need to read — not fill — the document.

How it works

Open the PDF Compressor
Navigate to ratpdf.com/pdf/compress in any modern browser.
Upload your PDF
Drag and drop your file or click the upload zone. Password-protected PDFs are supported if you enter the password.
Select compression level
Choose Recommended for balanced quality, Extreme for maximum size reduction, or Less for minimal quality impact.
Download the result
Click download when processing completes. Verify file size locally before submitting to portals or email.

Frequently Asked Questions

Use Recommended compression for balanced results. Less compression minimizes quality loss; Extreme maximizes size reduction for scans.

Lossless helps text PDFs but rarely shrinks photo scans enough for 100 KB portal limits. Combine lossless cleanup with image downsampling when needed.

150 DPI greyscale for ID documents; 200–300 DPI for detailed drawings. Higher DPI increases size without helping on-screen review.

Compression is one-way. Always archive your original file before distributing a compressed copy.

Best PDF Compression Settings

Lossless PDF Compression

Compress PDF Without Losing Quality

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