Reduce PDF file size for email attachments and faster sharing. Choose your quality level, preview the savings, and compress—all on your iPhone. No uploads to external servers.
Large PDFs create real problems. Email servers reject attachments over 25MB. Cloud storage fills up quickly. Downloads take forever on slow connections. Recipients get frustrated waiting for files to open.
Scanned documents are especially problematic. A 10-page scan can easily exceed 50MB when captured at high resolution. Multi-page reports with embedded images balloon to hundreds of megabytes.
PDF compression solves these problems by reducing file size while maintaining readability. A 20MB scan becomes a 5MB email attachment. A 100MB report fits in cloud storage. Documents open instantly instead of grinding for minutes.
Most PDF file size comes from embedded images. Compression re-encodes these images at lower quality, dramatically reducing size. A 5MB photo becomes a 500KB image—still clear enough to read, but 10x smaller.
Text and vector graphics (lines, shapes, charts) aren't affected by compression. These elements remain perfectly sharp regardless of compression level. Only raster images (photos, scans) are recompressed.
ScanLens uses intelligent compression that analyzes each image type. Photos get JPEG compression. Diagrams get optimized PNG treatment. The algorithm chooses the best approach for each embedded element.
Choose the right balance between file size and visual quality:
| Level | Quality | Typical Reduction | Best For |
|---|---|---|---|
| Maximum | 90% | ~15% smaller | Photos, portfolios, print-quality docs |
| High | 70% | ~35% smaller | Email attachments, general sharing |
| Medium | 50% | ~55% smaller | Screen viewing, web uploads |
| Low | 30% | ~70% smaller | Archival, text documents, drafts |
Maximum Quality: Use when image quality matters—photography portfolios, design documents, or files destined for printing. Minimal size reduction but maximum visual fidelity.
High Quality (Recommended): The sweet spot for most uses. Noticeable size reduction with minimal visible quality loss. Perfect for email attachments and professional sharing.
Medium Quality: Significant compression for screen viewing. Images look fine on displays but may show artifacts if printed large. Good for web uploads and quick shares.
Low Quality: Maximum compression for smallest files. Text remains readable but photos look soft. Use for archival storage, text-heavy documents, or when file size is critical.
Most email services limit attachments to 25MB. Gmail, Outlook, and Yahoo all enforce this. If your PDF exceeds the limit, compress it. High Quality usually brings files under the threshold while maintaining readability.
Free cloud tiers offer limited space—15GB for Google Drive, 5GB for iCloud. Compressing archived documents frees storage for more files. Low Quality works well for documents you rarely access.
Sharing documents via link? Recipients download faster when files are smaller. A 50MB PDF takes minutes on slow connections; a 10MB compressed version downloads in seconds.
If the PDF will be printed professionally, keep the original high-resolution version. Compression artifacts become visible in print. For legal archives requiring exact reproductions, also keep originals.
Know your email provider's limits when compressing PDFs for sending:
| Email Provider | Attachment Limit | Workaround |
|---|---|---|
| Gmail | 25 MB | Auto-converts to Google Drive link |
| Outlook | 20 MB | OneDrive integration |
| Yahoo Mail | 25 MB | Dropbox integration |
| iCloud Mail | 20 MB | Mail Drop for larger files |
| Corporate Email | 10-25 MB (varies) | Check with IT |
When a compressed PDF still exceeds limits, consider splitting the document or sharing via cloud storage link instead of attachment.
Typical results by compression level: Maximum quality reduces by ~15%, High quality by ~35%, Medium by ~55%, and Low by ~70%. Actual savings depend on content—image-heavy scans compress dramatically, while text-only PDFs see minimal reduction since text is already compact.
Compression reduces image quality proportionally to the compression level chosen. Text and vector graphics (charts, diagrams, logos) remain perfectly sharp at any level. For documents with important photos, choose Maximum or High quality to maintain visual clarity.
High Quality (70% image quality) is recommended for most email attachments. It typically reduces file size by ~35% while maintaining good readability. For documents with detailed images, use Maximum Quality. For text-heavy documents, Medium Quality works well.
Yes, ScanLens shows the estimated file size before and after compression. You see exactly how much space you'll save before applying any changes. If the reduction isn't sufficient, adjust the compression level and preview again.
No, all compression happens locally on your iPhone. Your documents are never uploaded to external servers. This keeps your files private and means compression works even without internet connection.
Download ScanLens free and shrink your first PDF in seconds. Choose your quality level, preview the savings, and compress—all processed locally on your device.