How to shrink a PDF so it fits in an email
Gmail and Outlook stop attachments at around 25 MB, and a scanned contract or a report full of photographs sails past that on its own. Here is what actually makes a PDF heavy and how much you can take off it.
First: find out what is heavy
A PDF is a container. Text weighs almost nothing — a hundred pages of plain text are a few hundred kilobytes. What weighs is images: a page scanned at 600 DPI in colour can be 3–5 MB on its own, and a phone photograph pasted into a page carries its full 4000×3000 pixels even though it is printed at 10 cm wide.
A quick way to tell them apart: open the file and try to select a word with the mouse. If the text highlights, the PDF has a real text layer and the weight is in its pictures. If nothing highlights, every page is a photograph and the whole file is images.
What compression really does
Compressing a PDF means re-encoding its images at a lower resolution and a lower JPEG quality, and throwing away what a printer would need but a screen will not. The text is untouched: it stays selectable and searchable.
That is why the result depends so much on the document. A 30 MB file of scanned pages can drop to 3 MB and still be perfectly readable on screen. A 2 MB file that is only text may not drop at all, because there is nothing heavy to take out — and a tool that swears it shrank it anyway is usually lying to you or damaging it.
How far to go
Pick by destination, not by the biggest number. For reading on screen or sending by email, a medium profile is plenty: images end up around 120–150 DPI, which a laptop or a phone cannot tell apart from the original. For printing, stay at 300 DPI: below that, thin lines and small type start to look muddy.
Compress the original, never a file you already compressed twice. Every pass re-encodes the same pixels and the damage adds up — that is where the blurry grey text everybody recognises comes from.
In CLEKARA's compressor the Smart mode tries a few sample pages before deciding, and if no profile achieves a useful reduction it hands your original back and says so, instead of returning a file that is barely smaller.
When it still does not fit
Split it. A 60-page report rarely needs to travel whole: splitting it into two or three parts is faster for everyone and keeps every page at full quality.
Send the pages that matter. If the other person only needs the invoice and the annex, take out the rest and send those.
If it is a scan, scan it again in grey or black and white at 300 DPI instead of in colour at 600. The file drops by three quarters before anything is compressed, and a contract does not need colour.
As a last resort, share a link from a cloud folder. It is not a defeat: for a file above 50 MB it is what the other side prefers too.
What not to do
Do not print to PDF again to make it lighter. That re-renders everything and usually loses the text layer: what arrives is a picture of your document, no longer searchable, and often not much smaller.
Do not upload a confidential document to a random site just to save two megabytes. Read who processes it first. A tool that does the work in your browser — CLEKARA does — never sends the file anywhere, which removes the question entirely.