Start with a fast size audit
Before changing settings, check why the file is large. In most cases, oversized PDFs come from high-resolution images, scan-heavy pages, and hidden document baggage. If you need immediate output, start with Compress PDF and compare before and after size on one representative page set.
- Image-heavy file: optimize image resolution first.
- Scanned file: tune OCR and scan settings next.
- Edited workflow file: remove metadata and hidden objects.
Step 1: Downsample images without blurring text
For most screen-first PDFs, 150 to 200 DPI is enough. For print workflows, keep around 300 DPI. Use JPEG for photo-heavy pages and avoid aggressive quality reduction on pages with small text.
If your PDF has mixed content, test one page with charts and tables first. Do not batch-compress hundreds of pages before verifying readability on edge cases.
Step 2: Handle scans and OCR in the right order
Scanned PDFs are usually the largest. The safest sequence is: merge pages if needed, clean scan quality, then run OCR once on the final file. This keeps search behavior and indexing consistent.
If your scanned pages are still images, convert them first with JPG to PDF, then continue compression on the final PDF.
Step 3: Remove hidden baggage
Large files often carry hidden weight: comments, old revisions, attachments, thumbnails, and full embedded font sets. Removing these usually saves space without changing visible layout.
- Strip metadata and old comments.
- Remove unused attachments and form artifacts.
- Prefer font subsetting over full embedding when possible.
Step 4: Trim and split before final export
Cropping alone does not always remove bytes. If only part of the document is needed, extract actual pages and re-export.
- Cut unnecessary pages using Split PDF.
- Rebuild final order with Merge PDF when needed.
- Compress once at the end for best output consistency.
Step 5: Run a final quality and compatibility check
Before sharing, open the compressed file on at least two viewers (desktop and mobile). Verify text clarity, table lines, chart labels, and searchable text behavior.
If quality regresses, step back one compression level rather than trying to repair after distribution.
Compression presets by use case
- Email and chat: prioritize smaller size and fast open time.
- Web delivery: balance size with readability on mobile.
- Print handoff: preserve detail, then optimize only if required by upload limits.
Privacy note for sensitive documents
If your PDF includes legal, HR, medical, or finance data, use local-first processing so documents stay on your device. Then apply access controls with Protect PDF before sharing.
Final checklist before sharing
- Compare file size before and after compression.
- Check one dense page for blur or artifacting.
- Confirm OCR searchability where required.
- Keep an uncompressed master copy.
Related workflow links
For adjacent tasks, use Compress PDF, PDF optimization guide, and the blog index.
Frequently Asked Questions
What is the safest way to make a PDF file smaller?
Use a staged process: audit size drivers, downsample images, clean scans and metadata, then validate one sample page before batch export.
Which DPI should I use for smaller PDFs?
For screen-first documents, 150 to 200 DPI is usually enough. Keep around 300 DPI for print workflows.
Does cropping a PDF always reduce file size?
No. Cropping can hide content without removing bytes. Re-exporting after trim is what usually reduces actual size.
Should OCR happen before or after compression?
For scanned bundles, merge and clean first, then run OCR once on the final file to keep search behavior consistent.
How do I compress sensitive PDFs safely?
Use local-first tools so files stay on your device, and verify output quality before sharing.