How to compress a PDF for email — and get under the limit

The scenario never changes: the attachment limit is 20–25 MB, and your PDF weighs 31. A cloud link is one way out, but plenty of recipients — corporate mail filters, print shops, government forms — want the file itself, in the message. That leaves compression, and here most guides send you to an online compressor that uploads the entire document to a server first. This guide takes the other route: shrinking the file on your own machine, in the browser, with nothing uploaded — then the practical details that decide whether the result clears the limit: which level to pick, how far each kind of document can actually shrink, and what to do when compression alone is not enough.

Compress a PDF in your browser, step by step

The fastest path is the Compress PDF tool on this site. Everything runs locally — the file is weighed, read and rewritten on your device.

1. Open the compress tool and drop your PDF anywhere on the page, click to browse, or paste it from the clipboard.
2. Pick a level: Light, Balanced or Strong. For email, Balanced is the right first try — most files shrink visibly with no obvious loss.
3. Click Compress PDF. Pages are processed one by one with a live counter, and the Cancel button genuinely works mid-run.
4. Read the result card: it shows the new size and how long the run took.
5. Download the smaller file and attach it. If the tool could not beat your original, it says so and hands back the untouched original — no fake wins.

Light, Balanced, or Strong — one honest trade-off

The three levels are really three statements about what you are willing to lose.

Light tidies the file losslessly: same content, written into a modern container. Text stays text — selectable, searchable, identical in quality. Choose it for documents that must remain machine-readable: contracts to sign digitally, files destined for indexing or long-term archiving. Expect modest savings; a well-made text PDF is already tight.

Balanced re-encodes pages with settings you will struggle to see. This is the level for the email case: providers cap attachments around 20–25 MB, and if you are just over, Balanced is usually enough to clear the bar. Text remains selectable at this level.

Strong squeezes hardest and turns text into images to do it — pages stop being searchable and selectable, and the label says so upfront. Reach for it when the size limit matters more than the text: a reference copy for a portal with a hard upload cap, an attachment nobody will quote from.

One honest caveat cuts the other way too: if the tool reports that the document is already optimized, believe it. Forcing more would only trade quality for nothing.

How much smaller — by document type

Savings depend entirely on content, and pretending otherwise is how bad guides mislead their readers.

Scanned documents shrink the most — often 50–90%, because they are images already and re-encoding is where the wins are. Image-heavy marketing PDFs typically lose 30–70%. Text PDFs produced by modern tools often lose nothing at all — there is simply no fat to trim.

And there is a structural guarantee worth knowing: this compressor mathematically cannot hand back a larger file. When the compressed result would be bigger than the original, you receive your original bytes back with a note saying the document was already optimized. Some online services quietly return a grown file and call it success; the never-larger invariant makes that impossible here.

Trim before you squeeze

Compression is the last step, not the first. Removing dead weight beforehand compounds the savings.

Start by deleting the pages nobody needs — blank separator sheets, the duplicated appendix, twelve pages of boilerplate. A lighter document compresses better, and every page removed is a page the compressor does not have to fight.

If the file is still over the limit after a Balanced pass, split it and send the parts across two messages, or attach the summary and offer the full document on request. Two modest PDFs that arrive beat one perfect PDF that bounces.

For batch jobs — the same fifty files every week — a desktop script eventually pays off. For the document in front of you, installing nothing is faster than installing anything.

Before it leaves your machine

Two habits close the loop. First, privacy: the compression runs in your browser on a background worker — financial reports, medical letters and legal filings are never uploaded, and you can compress with the network disconnected. Second, protection: a file light enough to travel is a file that will travel — give it a password before it goes, so the size work does not end in the wrong inbox.