Guides to compressing PDFs
How PDF compression really works, what gets lost along the way and how to get out of a jam when a form rejects your file. No impossible promises.
How to split a PDF by size: parts of 2, 5 or 10 MB
When a portal accepts several files but limits the size of each one, splitting the PDF beats compressing it: the pages stay untouched. Here's how to split it by size rather than by pages, what changes in the document and which other tools can do it.
· 8 min read
How to compress a PDF on iPhone, Android, Mac and Windows
Mac and iPhone have a built-in way to shrink a PDF; Android and Windows have none. And none of them lets you choose the final size. We explain what each option does, step by step, and how to hit an exact size on any device without uploading the file.
· 8 min read
How to email a PDF that's too large
Gmail, Outlook and Yahoo advertise 25 MB, yet a 20 MB attachment can still bounce. Here are the real limits of each provider, what size to aim for depending on who you're sending to, and the three ways out when the PDF won't fit.
· 8 min read
Why a PDF is so large and how to shrink it
Text takes up almost nothing: what drives up a PDF's size is scanned images and phone photos. We explain the pixel arithmetic, what each compression method does and which size to choose so the document stays readable.
· 8 min read
Compress a PDF without uploading it to any server
Most online compressors upload your document to someone else's server and ask you to trust that they'll delete it. There's another way to do it, and you don't have to take anyone's word for it: you can check it in thirty seconds.
· 7 min read
About these guides
These guides grew out of the questions that come up most when using the tool: why a ten-page document weighs over 10 MB, why a form rejects it even though it "should fit", or what happens to a PDF when you upload it to an online compressor. Each one explains the mechanism, gives figures you can check and ends with what you should do.
They're written and maintained by Robert Bzia, who develops the tool. When a figure depends on an outside service, such as email attachment limits, we say when it was checked, because those limits change. And if you want to know what takes up space in your own file, the PDF X-ray tells you without uploading it.