How to Compress a PDF Online — Free, Searchable Text Preserved, No Watermark

An email rejected your attachment because it was 25 MB. A government portal refuses anything over 5 MB. A client's photo-heavy proposal weighs 80 MB and the recipient is on 4G. Compressing the PDF before sending fixes all three problems in fifteen seconds — without flattening the text, without losing colours, without making the file look like a fax.

When you actually need to compress a PDF

Real cases we see daily: invoices with embedded vendor logos that bloat them to 15 MB, scanned contracts that come out at 300 DPI whether they need to or not, marketing decks where every slide has a full-resolution hero image, lecture notes that include the original textbook's scans, real estate listings full of camera-raw photos, board books pulled from a content management system without any optimisation.

The other common case: you want to email a normal-sized PDF, but you're sending it through corporate Outlook with a 20 MB cap and the original is 22. Most of the time the difference is one oversized image inside the file.

When NOT to compress

Don't compress files you'll print at high quality (full-bleed magazines, photo books). Compression trades image quality for size, and print magnifies what the screen forgives. For production print, keep the original.

How to compress a PDF, step by step

Open the Compress PDF tool

Go to convertpdfgo.com/compress. No account, no email, no installation.

Drop the PDF in

Drag the file onto the upload area or click to pick. Files up to 30 MB go through without a queue. Encrypted in transit (TLS 1.3), encrypted at rest, deleted within one hour.

Pick a level

Three levels: low (subtle), medium (sweet spot), high (most aggressive). Medium is the right default for emails and document handoffs.

Download

The output is a normal .pdf with the same content. Open in Adobe Reader, Preview, Chrome — text, search, copy-paste, bookmarks, embedded fonts all kept.

What we actually compress (and what we leave alone)

Compressed: embedded raster images. A 4000×3000 hero photo at 300 DPI inside a slide deck becomes 1600×1200 at JPEG quality ~75 on medium. Visually identical on a laptop screen, a tenth the bytes.

Compressed: redundant streams. Multiple identical fonts get deduped. Object streams get consolidated. PDF junk from generators (Word, LibreOffice, browser print-to-pdf) gets cleaned up.

Untouched: text. Glyph data is already efficient and shrinking it costs nothing in size while breaking searchability — so we never touch the text layer.

Untouched: vector graphics (charts, logos, line art). These are already small and compressing them only loses precision.

Low vs medium vs high — when to use which

Level	Image DPI	JPEG quality	Typical shrink	Best for
Low	200 DPI	85	20–40%	Print-ready handoffs
Medium	150 DPI	75	50–80%	Email, screen
High	96 DPI	60	70–90%	Mobile, archives

Common compression problems and how to avoid them

Output is barely smaller

The PDF was already compressed, or it's text-only with no images to shrink. There's no magic — if there's nothing to compress, compression can't help. Try high level; if that doesn't move the needle either, the file is already optimised.

Images look blurry after compression

You picked high on a file that needs to be readable at zoom. Step down to medium or low. The rule of thumb: medium for emails read at fit-to-page; low for files that might be zoomed in.

The PDF is password-protected

Compress can't open what it can't read. Remove the password via our unlock tool first (using the password you have), compress, then re-protect with our protect tool.

A short word on privacy

Three things to know. One: files go over TLS 1.3. Two: files are encrypted at rest while we process them, then deleted automatically within one hour. Three: we don't look at your files, train on them, or send them anywhere.

How we compare to other free PDF compressors

Feature	convertpdfgo	Smallpdf	iLovePDF
Sign-up	None	After 2/day	Optional
Watermark	None	None	None
File size cap	30 MB	5 MB	25 MB
Level picker	Low / Med / High	One level	2 levels
Auto-delete	1 hour	Vague	2 hours

Frequently asked questions

Will text searches still work after compression?

Yes — text is never rasterised. Searches, copy-paste, OCR layers all keep working.

How small can the output get?

Image-heavy PDFs commonly go from 20 MB to 2 MB on medium. Text PDFs shrink less because there's less to compress.

Does it work on scanned PDFs?

Yes. Scanned PDFs are typically image-heavy, so they shrink dramatically — sometimes 80-90%.

What about embedded fonts?

Fonts are deduped and subset where possible — multiple copies of the same font become one shared copy.

How long does it take?

About 1-2 seconds per MB. A 20 MB file takes ~30 seconds.

What's the file size limit?

30 MB as a guest, 50 MB when signed in.

Is there a usage limit?

No. Free, no daily cap, no sign-up wall, no watermark.

What to do next

One-click follow-ups

Now that the PDF is smaller, you can merge it with others, protect it with a password, sign it, or watermark it. All free.

Or browse our full list of 49 free PDF tools.