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PDF Compression Guide
A practical, trust-focused resource for shrinking PDF files for email, uploads, resumes, invoices, and document sharing.
Why this matters
PDF compression is about keeping files practical, not just smaller.
Large PDFs slow down email delivery, trigger portal upload limits, and make archives harder to manage. Thoughtful compression preserves readability for resumes, invoices, contracts, and client packets while avoiding unnecessary visual loss.
Privacy note
For sensitive documents, browser-based workflows are the safer default. Review the processing notice on each tool page so you know when a file stays in your browser and when a workflow uses a network-assisted route.
Guide
What compression means
Compression reduces file size by removing redundant data, optimizing embedded images, and trimming metadata without changing the document meaning.
Guide
Lossless vs lossy
Lossless compression preserves the original structure and text. Lossy compression can shrink files further by lowering image quality, which is often appropriate for web sharing.
Guide
Image-heavy vs text-heavy
Text-heavy PDFs are usually easier to compress because they contain less visual data. Image-heavy scans or marketing brochures need more careful tuning.
Guide
Why DPI matters
Higher DPI creates sharper scans but far larger file sizes. Lowering DPI can be a smart trade-off for email and web uploads.
When to compress each file type
Email attachments
Use a moderate compression setting so the document stays readable but leaves enough room for the message and any attachments.
Upload portals
Portal limits often require a smaller file than a printer-ready archive. Keep the original until you confirm the output is still acceptable.
Resumes and invoices
Preserve text clarity and form structure. Compression should not blur signatures, logos, or important line items.
Common mistakes to avoid
- Over-compressing scanned forms until signatures become unreadable.
- Using the highest compression setting for every PDF without checking the result.
- Forgetting that vector text and line art behave differently than scanned photos.
- Sending the only copy before confirming the output still opens cleanly on another device.
Online compression vs desktop software
| Option | Best for | Privacy | Trade-off |
|---|---|---|---|
| Browser-based tools | Fast one-off tasks, quick email attachments, public uploads | Often local-first for the standard workflow | Less setup, easy to review |
| Desktop software | Batch jobs, advanced export settings, large organizations | Depends on the app and storage setup | More control, more setup |
Related Letido tools
Frequently asked questions
Does compressing a PDF reduce quality?
It can, but the impact depends on whether the file is mostly text or image-heavy. Letido’s standard compression path aims to reduce size while keeping text and vector content readable, and you can review the result before sharing it.
What is the best PDF size for email?
Most email providers accept attachments around 5–10 MB comfortably, but some corporate mail systems and upload portals are stricter. A compact PDF under 2–5 MB is usually safer for quick delivery.
Why is my scanned PDF so large?
Scanned pages often contain large raster images. When a scanner saves at 300 DPI or higher, the file can balloon quickly. Reducing the image DPI or using OCR and re-exporting can slim it down.
Can I compress a PDF without installing software?
Yes. Browser-based tools such as Letido’s PDF compressor can shrink many files directly in the current tab, without requiring a desktop app or a signup.
Is PDF compression safe?
It is safe when you use a trusted tool and review the result. For sensitive records, use a browser-based utility and avoid sharing private information beyond the workflow you are performing.