Why a PDF gets so big
A PDF is a container. Inside it there are pages, fonts, text and, often, images. Text is stored as characters, which takes very little space. A page of plain text is usually only a few kilobytes.
Images are different. A photo or a scanned page can take hundreds of kilobytes or several megabytes, and a document with many of them quickly grows past the size limit of an email or an upload form. So when a PDF is large, the cause is almost always its images, not its words.
Two ways to make a PDF smaller
There are two common approaches, and they have different trade-offs.
- Recompress the images inside the PDF. The pages stay as they are. Only the photos and scans are saved again at a lower quality or resolution. Text remains real text, so you can still select, copy and search it.
- Turn every page into an image. Each page is drawn, then saved as one picture. This can give a very small file, even for complicated pages, but the text becomes part of the picture. You can no longer select or search it, and a PDF that was mostly text can come out bigger than it started.
Which one is right depends on what you need the file for.
When to keep the text
Choose the first approach when someone has to work with the document after you send it. For example:
- A report or contract that people will search for a word or copy a sentence from.
- A document read with a screen reader, which needs real text to read aloud.
- A file you may need to quote, annotate or translate later.
When a smaller file matters more
The second approach is fine when the PDF is only going to be looked at, and the size limit is the problem. A scanned form that must fit an upload limit, or a long set of photos saved as a PDF, are good examples. These files usually have no real text to begin with, because a scan is already just a picture of paper.
How to do it with Velfile
- Open Compress PDF and choose your file.
- In Mode, pick Keep text to shrink only the photos and scans. Pick Smallest file if you do not need the text to stay selectable.
- In Compression level, start with Balanced. Use Light when image quality matters, and Maximum when you need the smallest result.
- Press Compress PDF, check the result, then download it.
Everything happens in your browser. The file is processed on your own device and is not uploaded to a server.
If the file did not get smaller
Sometimes a PDF barely changes. That is normal when the file has little to shrink: a PDF made from a word processor, with only text and a few small images, is already compact. In Keep text mode Velfile tells you when there are no images it can reduce, and it does not offer a download that saves nothing. If your PDF is a scan, try Smallest file mode, or try a stronger compression level.
A few habits that help
- Keep the original. Compression of images cannot be undone, so save the smaller file under a new name.
- Check the result before you send it. Open the compressed PDF and look at the pages that matter, such as signatures, small print and photos.
- Split long files. If a PDF is very long, Split PDF lets you compress it in parts.
- Shrink images before you make the PDF. If you are building a PDF from photos, use Compress Image or Resize Image first, then JPG to PDF.
Last updated: 9 October 2026