Compress PDF

How do you make a PDF smaller?

Drop the file onto the tool above, choose one of the three settings, look at the pages on the right, and press Save PDF. The After figure updates as the pages render, so you know roughly what you are getting before you commit. Most scanned documents come down by somewhere between half and nine tenths.

If the first setting does not get you under the limit, move to the next one and watch what happens to the pages. That is the whole reason the preview is there: “small enough” and “still readable” are a trade, and only you can see where the line is for the document in front of you.

Why is my PDF too big to email?

Almost always because it came out of a scanner or a phone camera. A page of typed text is a few kilobytes; a photograph of that same page is several megabytes, and a scanner produces the second kind even when the original was the first. Twenty scanned pages will clear 20 MB without trying, and most school mail systems stop somewhere around 10 MB.

The tell is simple. If you can select the text with your mouse, the file is small already and compressing will barely help. If the text is part of the picture and cannot be selected, it is a scan, and this is exactly the file this tool is for.

What do you lose by compressing a PDF?

Each page is redrawn as a picture, so the text inside it stops being text. It looks the same and it prints the same, but it can no longer be selected, searched, or read aloud by a screen reader, and no later tool will be able to pull the words back out.

For a scan that costs you nothing, because the words were never selectable in the first place. For a document that was proper text — a policy, a letter, a worksheet made in Word — it is a real loss, and it is why the tool says so in plain words on screen rather than burying it. Keep your original either way. There is no un-compressing.

Which setting should I use?

Start with Balanced — 150 dpi is what a school photocopier scans at anyway, so it very rarely looks worse than the paper did. Move outwards only if you have to.

Setting	When it is the right one
Light	Something with a photograph or a diagram in it that people will look at closely. Barely different to the eye, and still a useful saving.
Balanced	The default, and the answer nine times out of ten. Fine for anything that is going to be printed and handed out.
Strongest	When a size limit is refusing the file and nothing else has worked. Check the pages on the right before you save this one — small print is where it shows first.

Will compressing spoil it when I print it?

Not at Balanced, for anything typed. The page keeps its original paper size and only the amount of detail inside it changes, so an A4 sheet still prints as an A4 sheet. What suffers first is fine detail: small print, thin lines on a diagram, and the edges of letters in a poor scan.

The honest test is the one the tool gives you. Look at the smallest text on the right-hand pages. If you can read it on screen, it will print.

Can you compress a PDF without uploading it?

Yes — this one never sends your file anywhere. Both the redrawing and the writing happen in your browser, which you can prove by turning the wi-fi off once the page has loaded and using it anyway.

That is worth more than it sounds for this particular tool. The documents teachers most often need to shrink are scans: a signed form, a chronology, a set of assessment papers, a medical letter. Those are the last files that should be handed to an advert-funded website in exchange for a download.

Compressing, or taking pages out?

If the file is too big because it has forty pages and you only need six, compressing is the wrong tool — dropping the other thirty-four will do far more, and costs nothing in quality. Take the pages out first, then compress what is left if it is still too heavy. In that order the two together will shift almost anything.