How to get a PDF under 100 KB or 200 KB for an online application

University portals, job sites and government forms love tight upload limits: 100 KB for a certificate, 200 KB for an ID, 500 KB for a whole application. Then you scan a single page on your phone and the file comes out at 4 MB.

The limit isn't arbitrary. Portals keep thousands of applications, and a reviewer has to open them quickly. You can almost always get under it without making the document unreadable, as long as you know where the size is coming from.

What makes a PDF big

Text is tiny. A ten-page letter typed in Word and saved as PDF is often under 100 KB already. Size comes from images, and in documents people upload, the images are usually the pages themselves: photos or scans of certificates, IDs and mark sheets.

A modern phone photo is 12 megapixels or more. That's far more detail than a reviewer needs to read an A4 page, and it's stored in colour even when the page is black text on white paper. So the job is nearly always the same: make each page image smaller in pixels, store it in a way that suits the content, and leave out anything that doesn't need to be there.

If you're starting from photos

Don't make a huge PDF and then shrink it. Build the PDF at the right size in the first place.

1. Take the photo square-on, in daylight, with the page filling the frame. A tilted page wastes pixels on the table around it.
2. Crop to the paper. Margins of carpet and fingers are still pixels.
3. Think about colour. Certificates with a coloured seal should stay in colour, but plain text pages compress much better in black and white. If the file is still too big, run it through Compress PDF with "Black & white" ticked.
4. Set the limit before you save. Our image to PDF tool takes your photos and a target such as 200 KB, and lowers the quality step by step until the whole file fits.

If you already have the PDF

Run it through a compressor with a target size rather than a vague "high/medium/low" setting. Ours re-draws each page as an image and keeps trying smaller sizes until the file is under your limit, so you can type 100 and get a file under 100 KB, or the closest it can get while still readable. For pages that are just black text, tick "Black & white" as well; plain text pages get noticeably smaller in black and white.

Two things to know about that approach. The pages become images, so the text can no longer be selected or searched; for an upload that's normally fine. And if the PDF is already mostly text, compressing it this way can make it bigger, not smaller. If a text-only PDF is over the limit, the cause is usually an embedded high-resolution logo or a scanned signature, and re-saving it from the original program at a lower image quality fixes it.

When it still won't fit

Some combinations are simply impossible. Ten scanned pages under 100 KB means about 10 KB per page, which is too little for anyone to read small print. When you hit that wall:

• Upload only the pages they asked for. If the form wants your passport's photo page, send that page, not the whole passport. Split the PDF and keep what's needed.
• Check whether the portal allows several files. Many accept one file per document type.
• Lower the resolution before the quality. An A4 page at around 1000 pixels wide is still readable on screen; at 600 it starts to struggle.

Check before you upload

After compressing, open the file and zoom to 100%. Can you read the smallest text that matters: the registration number, the date of birth, the grade? If you can't, the reviewer can't either, and an unreadable document can get an application rejected just like a missing one.

A few other things trip people up:

• Passwords. Portals usually can't open protected PDFs. Remove the password before uploading.
• File names. Some older systems choke on spaces and symbols. "ssc-certificate.pdf" is safer than "SSC Certificate (final) #2.pdf".
• File type. If the form says PDF, a JPG renamed to .pdf won't work. Convert it properly.
• Keep the original. Save the full-quality file somewhere safe. You'll need it the next time a form asks for a different limit.

Why our tools work in the browser

Certificates, IDs and mark sheets are exactly the kind of documents you shouldn't upload to a random website just to make them smaller. Every Memento tool processes files on your own device: nothing is sent to a server, so there's nothing for anyone to keep.