Compress PDF
Reduce PDF file size online free. No signup, 100% browser-based. Compress PDFs for email, web upload. Keep quality while shrinking files.
The PDF compression tool reduces file size by re-encoding images and optimizing fonts. Embedded high-resolution images are downsampled to more reasonable resolutions, unused font glyphs are removed, and content streams are recompressed. The entire process preserves document readability and layout structure, with text and vector graphics remaining virtually lossless at low compression levels.
Typical use cases include email attachments exceeding size limits, online form or web upload file size restrictions, and storage optimization for large-scale document archiving. Whether sending contracts, submitting application materials, or organizing scanned documents, oversized PDFs create transmission and storage inconveniences that compression quickly solves.
All processing is done locally in your browser. PDF files are never uploaded to any server, and confidential documents remain on your device throughout the compression process. This also means no queuing or server processing delays — compression speed depends on your local device performance.
How to Compress a PDF File
Upload your PDF file
Click the upload area or drag in PDF files. You can select multiple files for batch compression.
Choose compression level
Select from Low, Medium, or High compression levels. Higher levels yield smaller files but greater image quality loss.
Click compress
The tool re-encodes images and optimizes fonts based on your selected level. Processing time depends on file size and page count.
Download the compressed PDF
Download the result file after compression completes. Compare the size before and after to confirm quality meets your needs.
Core Features
Three Compression Levels
Low compression prioritizes quality, reducing size by ~20-40%. Medium balances quality and size, reducing by ~40-60%. High maximizes reduction at ~60-80%. Choose based on your needs.
Smart Image Compression
Automatically identifies and downsamples high-resolution embedded images. Reduces excessive DPI to levels suitable for screen viewing and printing, significantly reducing size with virtually imperceptible quality loss.
Font Subsetting
Embeds only the glyphs actually used in the document, discarding unused characters. For documents using large CJK fonts with limited text, this can dramatically reduce embedded font size.
Batch Processing
Upload multiple PDF files at once and compress each independently with the same level. All processing happens locally with no server upload — each file can be downloaded individually after compression.
| Compression Level | Description | Typical Reduction | Quality Impact |
|---|---|---|---|
| Low Compression | Prioritizes quality for printing and archiving | ~20-40% | Virtually no visible loss |
| Medium Compression | Balances quality and size for everyday sharing | ~40-60% | Slight quality reduction |
| High Compression | Maximum size reduction for email and web | ~60-80% | Visible image compression |
Use Cases
Email Attachment Compression
When your PDF exceeds the 10MB email attachment limit, use Medium or High compression to quickly bring the file under the limit without splitting or using cloud storage links.
Web Upload Optimization
Online forms, government portals, and job platforms often impose file size limits. Compress PDFs to meet these restrictions while retaining sufficient clarity for review.
Archive Storage Savings
Batch archiving of documents can consume significant storage. Compression reduces storage space and backup costs. Particularly effective for scanned documents which typically contain many high-resolution images.
FAQ
How much can PDF file size be reduced?
It depends on the content. Image-heavy PDFs at High compression can shrink by 60-80% since images are the largest size contributor. Text-only PDFs with embedded fonts may only see 10-20% reduction, as vector text and font data are already compact. See the compression level table for expected rates.
Does compressing a PDF reduce image quality?
It depends on the compression level. Low compression applies minimal resampling to images, making results virtually indistinguishable from the original. High compression significantly downsamples images to smaller resolutions, which is visible when zooming in but acceptable for screen reading and email attachments. Start with Low and increase only if the file remains too large.
What’s the difference between compression levels?
Low preserves image quality with ~20-40% reduction and virtually no visible degradation. Medium balances quality and size with 40-60% reduction and slight image softening. High maximizes size reduction at 60-80% with visible quality loss. Choose based on your PDF’s use — screen viewing tolerates high compression better than print.
Can I compress a PDF without losing quality?
Low compression is effectively lossless for vector text and line art, as these are not re-encoded. Embedded raster images may undergo slight resampling, but this is imperceptible under normal viewing. If your PDF contains only text and vector graphics, any compression level will not reduce quality.
Why is my PDF file so large?
The most common causes are high-resolution embedded images, complete font embedding (including unused glyphs), and uncompressed content streams. Scanned documents are typically very large because each page is a full-resolution raster image.
Can I compress multiple PDFs at once?
Yes. Upload multiple PDF files and each will be compressed independently with your selected level. All processing is done locally in your browser — no server upload needed. Each compressed file can be downloaded individually.