The document workshop / Devices

Compress PDFs on Phone or Desktop

Phone or laptop, the file stays on your device — but big PDFs behave differently on each.

The browser on your device does the work. The tool rejects inputs above 50 MB or 200 pages, checks a 16-megapixel ceiling before each raster allocation and stops a task after five minutes. Exactly 50,000,000 input bytes and 200 pages are within the stated input limits; successful completion still depends on the document and available memory.

A phone may run out of memory before those safeguards are reached, and a desktop is not unlimited either. Page dimensions, images, mode, browser and other open tabs all matter. Try from the original on a device with more memory, or split with a separate editor when the destination accepts parts. Fast has one rendering pass, but it is not a memory guarantee.

The same engine and preset settings are used on each supported browser. JPEG encoding can vary across browsers, so byte-identical output is not promised. Physical-device testing is separate from responsive browser checks. A transformed copy loses live text and PDF features on every device; an original kept unchanged retains them.

Match the mode to the task.

Targets are best effort. The final size and warnings are shown with your result.

Choose an approach
Your situation	Mode	What to expect
Everyday file on a phone	Email	Balanced colour settings. Try a short file and inspect the result on the device you use.
Large or 100+ page PDF on a phone	Fast	One rendering pass may reduce work, but cannot guarantee completion. Processing limits apply and automatic colour handling may use grayscale.
Big file on a laptop or desktop	Under 10MB	A numeric target only when 10MB is the required cap. All processing limits still apply and grayscale may be used.
Scan from a phone camera	Scanned	For monochrome scans only: grayscale discards colour. Inspect writing, stamps and highlights before using the result.
Just need it done fast	Fast	A single quick pass for when you're in a hurry on any device.

Articles & resources.

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Frequently Asked Questions

Why is compression slow or failing on my phone?

The work happens in your phone's memory, so a very large or very long PDF can simply be too much for it. Try a desktop browser, or split the file into smaller parts.

Does my file get uploaded when I use a phone?

No — on every device, the PDF is processed inside your browser and is not sent to our servers. The device changes the speed, not the privacy.

Which device gives the best result?

More memory can help a task finish, but it does not prove higher visual quality. The same preset settings apply; browser encoders can differ. Inspect the output on the device and viewer that matter.

Put the advice to work.

Mode: Email. Review the result before sharing your file.

Start compressing