You finish a contract or a report, hit send, and the email bounces: the attachment is over the size limit. Or a web form only accepts PDFs under 5 MB and yours is 18. The document looks ordinary, yet it weighs too much — and the cause is almost always the images packed inside the pages. Here is how to shrink it without turning the text into mush.
Why a PDF gets heavy
Text itself takes up almost no space. What inflates a file is images: scanned pages, photos, high-resolution logos, screenshots. A passport scan at 600 dpi can be several megabytes per page. If you built the document from phone photos, each one drags its full 3–5 MB original along.
The other source of bloat is embedded fonts and duplicate copies of the same picture that the software never merged. Compression handles that part automatically.
How to compress a PDF, step by step
1. Open the compress-pdf tool and upload your file. 2. Pick a compression level. For email, a medium setting usually shrinks the file noticeably while keeping it readable. 3. Wait for processing and download the result. 4. Open the compressed file and scroll through all of it — especially pages with scans, stamps, and signatures. 5. If it is still too big, apply a stronger level or drop extra pages with **remove-pages**.
A real-world example
A reader needed to email a 22 MB scanned lease to a landlord whose inbox rejected anything over 10 MB. A medium compression pass on **compress-pdf** brought it to 6 MB, the signatures stayed legible, and the email went through on the first try. The whole fix took under a minute — no quality settings tuning, no retries.
What can go wrong
- **The text looks blurry.** You picked too aggressive a level for a scanned document. Step back to medium — the size difference is usually small and readability returns.
- **The size barely changed.** That means the file was already a clean text PDF from Word or Google Docs, with little to compress. The problem is elsewhere; recheck the form's requirements.
- **Still over the limit.** For multi-page scans, split the document with **split-pdf** and send the parts separately.
- **A color scan that could have been black and white.** If color is not needed, convert the pages to grayscale with **pdf-to-grayscale** and watch the size drop.
A common mistake
The common mistake is compressing once, seeing a small file, and sending it without opening it. Aggressive settings can quietly blur a stamp or a handwritten signature that the recipient actually needs to read. Always open the result and check those spots before you send.
What to check before sending
- The file fits the email or form size limit.
- Text is readable without zooming; stamps and signatures are distinct.
- All needed pages are present and no extras slipped in.
- The filename is clean and descriptive.
When a document has to hit a specific size, drop it into **compress-pdf** and dial in the level for your case. For long files, **split-pdf** and **remove-pages** help trim it down before you send.