For example, you should use strong compression if you need to get the file size below a certain limit for online submission but not if you are just trying to make the file a little smaller. This is all to say, don’t use the strong compression unless you really need to. What do I mean by this? Basically, if you have images in the file and use strong compression, your images could seem blurry afterwards. You may lose some image quality, for example, or the quality of the data may suffer a little. On the other hand, if you use strong compression, some things will be slightly different.

When you use our basic compression, the file size will go down around 40%, but the image quality and the stored data in the file won’t be affected much, if at all.

So, if it’s entirely text then it will compress at a different rate than a PDF with lots of images in it.

A lot of times, the contents of your original document can affect the compression rate. So, it’s worthwhile pointing out that the rates given here are estimates but they are still very strong.

Free online pdf compression tool