Why your PDF won’t go under 1 MB
What makes a PDF big, why a scanned page sets a floor no compressor gets under, and a two-step way to meet an upload limit
Drafted with help from AI. Every size in this story was measured: four sample files went through the tool, and we read back what it saved.
The scholarship form is clear about it: upload one PDF, no larger than 1 MB, with the form itself, your degree certificate, a reference letter and your transcript. You have all four. The form is a PDF you filled in. The certificate and the letter are photos you took with your phone. The transcript came out of the college’s scanner. Put together, they weigh 7.4 MB.
Compress the merged file, and it won’t go under 1.6 MB, however hard you squeeze. Here’s why, and how to get under the limit anyway.
Text is cheap, pictures are not
A typed page keeps its text as text: the letters, where they go, and the shapes to draw them with. The two-page form, about a thousand characters, weighs 80.2 KB.
A photo keeps every pixel. A phone camera takes 12 million of them (4032 × 3024), and even saved as a JPEG, each of these photos weighs 2.9 MB: nearly three times the limit on its own.
A scan is a photo too, even when all it shows is text. The scanner saved each page of the transcript as a picture of 2480 × 3508 pixels, 300 to the inch, about 800 KB a page. There’s no text in that PDF at all: try to select a word, and you can’t.
A compressor can only shrink pictures
Making a PDF smaller means saving its pictures again in fewer bytes: at a lower JPEG quality, with fewer pixels, or both. A page of real text has almost nothing to give.
When PDFs are merged, their pages are copied as they are. That’s what keeps your typed form sharp and its text selectable, and it’s the right default. But the scan is copied as it is too: 1.5 MB of pictures the compressor never touches. Shrink the two photos as far as you like, and the merged file still can’t go under the form plus the scan.
That’s what the PDF Builder told us when we asked it for 1 MB: at standard quality the PDF comes to about 3.9 MB, the smallest it can go is 1.6 MB, and the target can’t be reached.
The one-click fix, and what it costs
There’s a box for this: Also compress pages taken from PDFs. It redraws every page that came from a PDF as a picture, which can then be shrunk like a photo. Tick it, and the whole application fits: 972.1 KB.
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But “every page” includes your typed form. Its two pages are pictures now: none of its thousand characters can be selected, searched, or read aloud by a screen reader. And a page of text costs more as a picture, not less: on their own, the form’s two pages come to 191.7 KB as pictures, against 47.2 KB copied as they were.
Two steps instead
The scan is the only PDF that needs redrawing, and it loses nothing by it: it was pictures of text already. So shrink it on its own first, then merge.
Step 1: the scan alone. Add only the transcript, choose Compress, and tick Also compress pages taken from PDFs. Each page is redrawn at 1191 × 1684 pixels, 144 to the inch, and saved at 80% quality. The transcript goes from 1.5 MB to 218.7 KB.
144 pixels to the inch is sharp on a screen, where an application like this is read. On paper it’s softer, so keep the original scan for anything you’ll print.
Step 2: everything together. Add the form, the two photos and the smaller transcript, choose Fit a target size, and type 1. The smallest it can go is now 267.6 KB, so 1 MB is within reach. Build it: 974.2 KB, with the form’s pages copied untouched and every word on them still text.
How the builder gets under the limit
How big a JPEG comes out depends on what’s in the picture, so there’s no way to know in advance. The builder doesn’t guess: it builds the PDF, measures it, and tries again until it fits.
It lowers the quality first. But below about 60%, a JPEG starts to break into small square blocks, with ripples around the edges of letters. So the builder stops there and makes the pictures smaller instead, every one by the same share. Here, the two photos kept quality 60 and went from 4032 × 3024 to 3434 × 2575 pixels: still far more than a page needs on a screen.
“1 MB” is ambiguous, too. Some systems count a megabyte as 1,000,000 bytes, others as 1,048,576. The builder aims under 1,000,000, so the file passes either way. That’s why the result reads 974.2 KB: like Windows, the tool counts sizes in units of 1,024 bytes.
Before you upload
- Find what’s big before you compress: photos and scans are, typed pages aren’t.
- Shrink a scan on its own, then merge it with your typed pages.
- Open the result and read a page of each document before you send it.
These files carry your name, your date of birth and your grades, and many online compressors work by uploading them to a server. The PDF Builder we made does everything above in your browser: nothing is uploaded, and there’s no account.
What’s the smallest upload limit you’ve had to squeeze an application into?
