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Compress a PDF to Under 1 MB

One megabyte is the most forgiving cap a portal is likely to set, and a few pages scanned at 300 DPI will still sail straight past it. This page aims comfortably under a million bytes, so the file clears the limit whether the form counts a megabyte as 1,000,000 bytes or 1,048,576 of them.

PDF or PDF

Nothing uploadedNo sign-upNo watermarkHow that works

How to compress a PDF to under 1 MB

  1. Tap Choose the large PDF and pick the file.
  2. The target already reads 1 MB, so tap Compress to 1 MB.
  3. Give a long scan a moment — the biggest files take the longest here.
  4. Read the finished size and save the copy.

Which megabyte does the form mean

A megabyte is a million bytes to a disk maker and 1,048,576 bytes to Windows, and upload forms are written by people who have quietly picked one of the two. A file of 1,020,000 bytes passes one reading and fails the other. This page aims well under a million, which is inside the limit on either count, and prints the exact byte figure so you can check it against whatever the form displays.

That margin doubles as insurance on the last step. The document is written out and weighed for real before you are given it, and if it lands over the cap the tool drops a quality step and writes it again rather than handing you a guess.

What actually makes a scan heavy

A file of six or eight megabytes is almost always a document scanned at a resolution nobody will ever use. One A4 sheet at 600 DPI in colour is around thirty-five million pixels, and no portal, printer or clerk will look at more than a fraction of them. Bringing that down is where nearly all of the saving comes from, which is why a very large file can drop below a megabyte and look no different on screen.

The opposite case is a PDF that is large because it holds hundreds of pages of text. There is very little image data in a file like that, so an image compressor has almost nothing to take and the size will barely move. The first line of the result tells you which of the two you have, in numbers taken from your own file.

Questions

My PDF is already under 1 MB. Should I still run it?
There is no harm in it, but there may be no point. If nothing available can save at least three per cent, you get the original file straight back with a note saying why.
Is 1 MB the same as 1024 KB here?
The target is a million bytes, and the tool aims about ten per cent under it, so the result also clears the 1,048,576-byte reading. Both are covered without you having to work out which one your form meant.
What is the biggest file I can compress?
A hundred megabytes, one document at a time. The honest limit below that is your device: a phone with little free memory may struggle on a file that size well before the tool does.
Can I compress a PDF that has been signed?
A signature that is a picture on the page is re-encoded like any other image. A cryptographic signature will not survive, because the document is rewritten — so compress the file before it goes for signing, not after.

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