Reduce PDF File Size on Mac
How to reduce PDF file size on Mac without blurry text. Fixes the macOS Preview Quartz filter flaw with local vector-preserving compression.
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Paste from clipboard with Cmd+V · Multiple files supported
Supported: PDF
- Never uploaded
- No watermark
- No sign-up
- No server upload limits
How It Works
Simple 3-step compression powered entirely by your local browser
Add Your PDF
Select or drop the PDF from your device.
Choose a Compression Mode
Gentle focuses on structure; stronger modes may recompress large embedded images.
Download the Result
Review the new file size and output quality before using the compressed PDF.
Why Choose LessMB
The private, modern alternative to legacy cloud compressor websites
100% In-Browser Privacy
Zero bytes uploaded. Your personal photos, sensitive documents, and private videos never touch external servers or cloud storage.
Zero Queue & Instant Start
No waiting in cloud conversion queues or watching slow upload bars. Processing starts the millisecond you drop your file.
Hardware Acceleration
Harnesses WebAssembly SIMD and WebCodecs GPU encoding for high-fidelity compression directly on modern consumer hardware.
No Credit Consumption
Free tier compression uses your own device compute, meaning zero server credit drain for everyday single and batch tasks.
Current Platform Size Limits
Verified figures — platform limits change over time, so each row carries its check date.
| Platform | Limit | Verified |
|---|---|---|
macOS Preview (Quartz Filter) Built-in Native | Fixed preset | macOS built-in workflow |
Email attachments Provider dependent | Often 20–25MB | Provider rules vary |
LessMB Local Compressor Client-side | Gentle / Balanced / Strong | Matches the current LessMB PDF engine |
Tips for Best Results
- Use Gentle mode for contracts, forms, and PDFs where preserving embedded image quality matters more than maximum savings.
- Use Balanced or Strong only when you accept recompression of large embedded JPEG images in exchange for a smaller file.
- Vector text remains vector text; scanned "text" is actually an image and can blur if that image is resampled.
- For very large scanned PDFs, rescanning at an appropriate resolution can produce a better result than repeatedly recompressing the same source.
Frequently Asked Questions
Straight answers about this tool and how it works
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Tutorials & Guides
Deep dives from the LessMB editorial team
How to Compress a PDF Online Without Guesswork
See how PDF structure cleanup and image recompression affect file size, when stronger modes may reduce image quality, and how to choose the right mode.
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How to Compress Images Without Losing Quality
Learn how dimensions, format, quality settings, and metadata affect image size, plus how to reduce bytes without introducing avoidable blur.
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How to Compress Images to an Exact File Size
Set a target KB or MB size, understand why files miss hard limits, and use a browser-local workflow to verify the final output before upload.
Read guide