How to Compress a PDF to 100 KB

You can compress a PDF to under 100 KB by choosing the “Under 100 KB” target in the Compress PDF tool. It tries stronger and stronger settings until the file fits, and it tells you honestly if it cannot get that small.

A short document with a few pages usually reaches 100 KB. A long scan full of photographs often will not. This guide shows the steps, what to expect, and what to do when the file stays too big.

What you need

• The PDF on your phone or computer
• A minute or two
• A rough idea of how many pages you really need to send

Steps to get a PDF under 100 KB

1. Open the Compress PDF tool, tap the box and choose your PDF. The file stays on your device. It is not uploaded.
2. Under How much to compress, leave Medium (recommended) selected. The tool will move to stronger settings by itself if it needs to.
3. Under Target size (optional), choose Under 100 KB.
4. Tap Compress PDF and wait for the progress bar to finish. A PDF with many pages takes longer on a phone.
5. Read the result message. It says either that the file is under your target, or that it could not reach 100 KB and shows the smallest size it managed.
6. Download the file, open it, and zoom in on the text and any numbers. Make sure everything you need is still readable before you upload it.

What the tool does to reach 100 KB

The tool works in steps, from gentle to strong.

First it tidies the file without changing how it looks. Then it makes the photos inside the PDF smaller. If the file is still too big, it turns each page into a picture and lowers the sharpness of that picture a little at a time. It stops at the first step that fits under 100 KB.

That last stage matters. When pages become pictures, the PDF looks the same on screen, but you can no longer select, copy or search the text. For most upload forms this does not matter. If you need selectable text, keep the original file too.

Why PDF files get big

Most of the size of a PDF comes from pictures. A scan or a photo of a page is a large image, even when the page only holds a few lines of text. A page that was typed on a computer is usually tiny, because text takes very little space.

This is why two PDFs with the same number of pages can be very different sizes. A ten-page typed letter might already be under 100 KB. A ten-page scan from a phone camera can be several megabytes.

If the file will not go under 100 KB

Sometimes the tool reaches its limit. Try these, one at a time:

• Send fewer pages. Many forms need only the important pages. Use Split PDF to keep just those, for example by typing 1-2, 5. Fewer pages means a smaller file.
• Remove blank or extra pages. Organize PDF shows every page as a preview, so you can delete the ones you do not need.
• Make the photos smaller before you make the PDF. If you build the PDF from photos, shrink each photo first with Compress Image, then combine them with JPG to PDF.
• Scan in a plainer way. A black-and-white or grayscale scan at a normal size makes a much smaller file than a colour photo of the page.
• Trim the margins. If a page has wide empty borders, Crop PDF can remove them, which helps a little.

A note about “100 KB”

Some websites count one kilobyte as 1,000 bytes, and others count 1,024. The target in this tool uses 1,024. If a website rejects a file that is very close to the limit, choose a smaller target, such as 50 KB, and try again.

Common problems

The text looks blurry after compressing. The tool had to lower the sharpness to reach 100 KB. Try sending fewer pages, then compress again. With fewer pages the tool can keep each one sharper.

The message says the file is already under the target. Then nothing needed to change, and you can upload the original.

The result is bigger than I expected. The target is a maximum, not a promise to make the file as small as possible. If you want it even smaller, choose a smaller target.

Frequently asked questions

Will I still be able to select the text?

With the gentler steps, yes. If the tool has to go to the strongest steps to reach 100 KB, every page becomes a picture and the text can no longer be selected or copied. The result message and a warning on the page tell you when this happens.

Can I get a ten-page PDF under 100 KB?

It depends on what is on the pages. Typed text pages often can. Pages that are photos or scans usually cannot, because each page is a large picture. In that case the tool shows the smallest size it reached, and you can send fewer pages instead.

Is my PDF uploaded anywhere?

No. The compression runs inside your browser on your own device. Your file is never sent to our servers or anyone else.

What if the form says 100 KB but my file is 101 KB?

Choose a smaller target, such as 50 KB, and compress again. Websites measure size in slightly different ways, so it is safest to stay a little under the limit.

Do I lose quality?

Yes, if the tool has to use its stronger steps. A file that small has little room for detail. Check the result on your screen before you send it.